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ASSAULT RIFLES AND THEIR AMMUNITION: HISTORY AND PROSPECTS

Anthony G Williams, Editor IHS Jane's Weapons: Ammunition

Last amended November 2016 (major re-write)

Introduction First, I need to define what I mean by an "assault rifle", as there are various definitions around. The one I use is: "A standard military rifle, capable of controlled, fully-automatic fire from the shoulder,

with an effective range of at least 300 metres". This raises various questions, including: "what do you mean by effective range?". This is sometimes held to be where there is a 50% chance of the average soldier hitting a human target with a single aimed shot, but in more general terms could be expressed as the range within which aimed fire is likely to hit or suppress the enemy suppression meaning to deter the enemy from effectively fighting back or moving position, something which is achieved by near misses. Another obvious question is: "what do you mean by controlled?". There is no agreed definition, but the implication is that for automatic fire to be useful, the average infantryman should be able to keep short bursts of fire on a human target at short range, with a useful percentage of the bullets scoring hits. Controllability is affected by gun design the shape of the stock, the type of gun action, the use of muzzle brakes or suppressors, and especially the weight of the gun but the above definition of "assault rifle" has some clear implications for the ammunition such weapons are chambered for. First, it excludes weapons designed around pistol cartridges (i.e. machine pistols and sub-machine guns - SMGs) as they only generate around 500 joules (J) muzzle energy (ME) and cannot meet the range requirement. Second, it excludes the traditional "full power" (FP) military rifle/MG cartridges such as the .303" (7.7 x 56R) British, the .30-06 (7.62 x 63) US, the 7.92 x 57 German, the 7.62 x 54R Russian and the 7.62 x 51 NATO (typically firing 10-12 g bullets at muzzle velocities (MV) of 750-850 m/s and developing around 3,000-4,000 J), as these are so powerful that the recoil they generate is virtually uncontrollable by the average soldier using fully-automatic rifle fire from the shoulder. Ammunition developing MEs and recoil somewhere between the SMG and FP types is needed (ME and recoil are separate calculations, but broadly linked). The history of assault rifles is very much focused on the development of the ammunition which they use. It took some time for suitable ammunition to become available. Early efforts towards light automatic weapons saw pistols such as the Mauser C96 (7.63 x 25) and P08 Luger (9 x 19 Parabellum) modified to produce carbine derivatives with detachable stocks, usually only capable of semi-automatic fire but a few with a burst-fire option. These were relatively fragile and expensive to make, however, so the future in short-range automatics lay with the much simpler blowback SMG. The first of these in

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service (if you discount the curious twin-barrel Villar Perosa) was the Bergman MP18 in 9 x 19, which was the ancestor of the MP 38/40, the Sten Gun, the PPSh and so on. An honourable mention also to the Thompson, developed separately in the USA from 1916 onwards for their .45 Auto (11.5 x 23) cartridge. An oddity was the Pedersen Device of 1918, which replaced the bolt in the US Springfield Rifle with a semi-automatic mechanism to fire small .30 cal (7.62 x 20) pistol-type rounds developing less than 400 J; it was never used in anger. Attempts to improve the power and range of the SMGs, such as the development of the .45 Remington-Thomson in the experimental Model 1923 Thompson SMG (which used a very powerful loading developing almost three times the ME of the .45 Auto) and the use of the 9 x 25 Mauser round in the 1930s Solothurn S1-100 and Hungarian Kiraly 39M and 43M SMGs (which saw some service), did not catch on. There is a limit to the degree to which the performance of such weapons can be increased as their large-calibre, relatively light and round-nosed bullets lose velocity quickly. Also, the blowback operating system used by most SMGs is not suited to high-powered ammunition, although the Kiraly and Thompson M1923 had more sophisticated mechanisms.

.30 Pedersen (7.65 x 20), .30 Mauser (7.63 x 25), 9 x 19 Parabellum, 9 x 25 Mauser, .45 Auto (11.5 x 23), .45 Remington-Thompson (11.5 x 26), 5.7 x 28 FN, 4.6 x 30 HK,

5.8 x 21 DAP-92. More recently, small-calibre high-velocity PDW ammunition has emerged (described in more detail in a separate article1). The FN 5.7 x 28 has achieved some sales, in both the Five-seveN pistol and the P90 SMG, as has the rival HK 4.6 x 30 in the MP7. However, despite their improved range performance, these cartridges still only develop around 500 J so don't qualify as assault rifle ammunition. The Chinese 5.8 x 21 DAP-92 is even less powerful. At the other end of the power scale there were many attempts from the beginning of the 20th century to increase the firepower of the FP infantry rifle by replacing its manual bolt-action with a self-loading mechanism (some of them shown below). However, such weapons did not enter general service as standard infantry rifles until the US M1 Garand in 1937.

1 http://quarryhs.co.uk/PDWs.htm

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Some early semi-automatic rifles, from top to bottom: 1918 .303 Farquhar Hill; 1909

Mondragon (7.92 mm); 1917 MAT Mk 1917; 1929 Czech Brno Z.H.29 (photo taken at MoD Defence Academy, Shrivenham)

Attempts to make such weapons fully automatic ran into difficulties due to their heavy recoil. Perhaps the most successful examples were the WW2 German FG 42 paratroop rifle in 7.9 x 57 and the postwar Swiss Stgw.57 in 7.5 x 55, but these were significantly heavier than contemporary rifles, the weight helping to absorb the recoil. This is even more true of the US Browning Automatic Rifle (BAR) in .30-06 which was even heavier, weighing about twice as much as a "standard military rifle"; its low rate of fire also helped controllability. Some of the early rifles in 7.62 x 51 NATO, such as the US M14, German G3 and some versions of the FN FAL, were also capable of fully automatic fire, but the recoil problem made them more or less uncontrollable so they cannot be classified as assault rifles. Assault rifles therefore need to be designed around a cartridge intermediate in ME between SMG and FP rifle rounds; in practice, approximately in the 1,250-2,500 J range depending on the calibre. There have been two contrasting approaches to the design of a suitable cartridge with the appropriate compromise between long range and light recoil. One is to retain the same 7.5-8 mm calibre as the FP round, but with a shorter cartridge case firing a lighter bullet at a lower muzzle velocity (lets call these "full calibre assault rifle", or FCAR, rounds). The other is to reduce the calibre

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while retaining the same, or a higher, velocity (reduced calibre, or RCAR rounds). FCAR rounds score well in the traditional methods of measuring barrier penetration and terminal effectiveness (dominated by calibre and bullet weight) and also by being less affected by the bullets striking foliage etc on their way to the target. However, they have a relatively steep trajectory and a rapid velocity loss due to the short, fat bullets, which quickly reduces their effectiveness at long range.

The full-power 7.9 x 57, 7.5 x 55, .30-06 and 7.62 x 51, shown next to the 7.62 x 39 and 5.56 x 45 which are the most common FCAR and RCAR rounds respectively

A decision to reduce the calibre raises the immediate question; by how much? At the large end of the RCAR scale (7 mm), bullet weight and MV can be much the same as in the FCAR cartridges, but the better ballistic coefficient (BC) due to the longer and more slender bullet will reduce velocity loss and improve long-range performance. As the calibre decreases, so the recoil and the ammunition weight become lighter and the MV can be higher, thereby flattening the trajectory; all good things. The downside is that barrier penetration may be reduced and stopping power becomes more controversial (relying on velocity and rapid bullet yaw on impact rather than calibre and bullet mass; which according to combat reports sometimes works, sometimes doesn't). The long-range performance also begins to decrease as small-calibre bullets generally have BCs which are inferior to large-calibre ones. Different nations have made different choices in developing assault rifles, and the purpose of this article is to describe and explain them in order to examine the future prospects for this type of weapon.

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Developments up to 1918 The elements of an assault rifle were in place surprisingly early in the history of automatic weapons. The first selective fire (semi or full auto) rifle was probably the Italian Cei-Rigotti, developed between 1900 and 1905 around a 6.5 mm cartridge with less power and recoil than the usual 7.5-8 mm FP types, but this was not adopted. Mannlicher introduced a Self-Loading Carbine in 7.65 x 32 calibre, an improved and enlarged version of their Model 1901 pistol carbine chambered for a lengthened version of the 7.63 x 25 pistol round, which was made in 1904. It never went past the prototype stage and its ballistics are not known. However, the cartridge case is similar in length as well as calibre to the US .30 M1 Carbine's, but slightly fatter as it is bottle-necked.

Mannlicher Carbine in 7.65 x 32 calibre (courtesy of Geoff Sturgess)

The first service weapon which can be identified as conforming to the specification of an assault rifle dates back to the First World War; the Russian Federov Avtomat of 1916. This was a selective fire weapon using a short-recoil action. It was originally chambered for Federov's own purpose-designed high-velocity 6.5 mm cartridge, but as the Great War was then underway there was no chance of a new cartridge being adopted, so he modified his gun to use the Japanese 6.5 x 50SR Arisaka cartridge, large quantities of the guns and ammunition having been acquired by Russia to meet a shortfall in their supply of rifles. This was a happy accident, as the cartridge combined moderate recoil with a good long-range performance, but only a few thousand Avtomats were made. They were used in action in the Russian Civil War and also as late as the Winter War with Finland in 1939-40, and thereby earned their place in small-arms history.

Federov Avtomat

It can be argued that neither the Cei-Rigotti nor the Federov Avtomat used

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"intermediate" cartridges, as the 6.5 mm Carcano and Arisaka were the front-line rifle/MG rounds in the Italian and Japanese armies respectively. This is true, but it is worth bearing in mind that, in terms of calibre and muzzle energy, they were in the same class as the present-day 6.8 x 43 Remington SPC and 6.5 x 38 Grendel, which are today regarded by many as ideal intermediate cartridges for assault rifles.

8 mm Ribeyrolles

The French also nearly made it into the record books with the first selective-fire rifle using purpose-designed intermediate ammunition. During WW1 they made some use of the semi-automatic Winchester Model 1907 in .351" (8.9 mm) and the Model 1910 in .401" (10.2 mm) Win SL (self-loading) cartridges; the rifle design was very simple, being blowback only. While these were mainly used by aircrew, in 1917 France placed an order for 2,200 of an automatic version of the M1907 for use by special assault soldiers. At the same time, they were modifying the .351 SL cartridge by necking it down to accept an 8 mm rifle bullet, creating the 8 mm Ribeyrolles arguably the first purpose-designed intermediate military cartridge. This was tested in July 1918 and found to be effective out to 400 m. The war ended before anything came of this, but it is not hard to see that had it lasted for another year or two, French troops could have been equipped with an assault rifle. As it was, neither the Ribeyrolles, nor a 7 mm version designed in the 1920s, made further progress. Another very interesting weapon and ammunition combination which emerged in 1918-19 was the Winchester Machine Rifle in .345 calibre, designed by Frank Burton. The cartridge was simply the .351 Win SL loaded with a pointed 11.2 g (173 grain) bullet fired at an MV of 564 m/s (1,849 fps). The gun weighed 4.5 kg (10 lb) and was 116 cm long (45.5") with a barrel length of 63.5 cm (25"). It used a blowback action and fired from an open bolt; it had selective fire, with a cyclic rate on automatic of 800 rpm. The most interesting aspect was the unique ammunition feed, which consisted of two box magazines, top-mounted but in a vee-form or butterfly wing layout. The capacity of each magazine is commonly said to be 40 rounds, although the Winchester museum (which has the only surviving example) states 25 rounds. This layout had several advantages over other top-mounted magazine feeds: increased ammunition capacity without needing an excessively tall magazine an empty magazine could be replaced while keeping the gun instantly available to

fire using the other magazine the sights were ambidextrous: on the centreline with the sight-line between the

magazines, instead using sights offset to one side (as in e.g. the Bren gun). Unfortunately this weapon did not proceed past the prototype stage.

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Above and below: Winchester Machine Rifle, showing the unique magazine layout

6.5 x 52 Italian, 6.5 x 50SR Japanese Type 30, 7.65 x 32 Mannlicher, .351 Winchester SL, .345 Machine Rifle, 8 mm Ribeyrolles (replica)

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The interwar period Interest in assault rifles on the part of the major powers then largely disappeared from view until the Second World War, although experiments continued in some smaller countries, especially Switzerland. Their prolific gun designer Frrer produced a short-recoil carbine with a new bottle-necked 7.65 x 35 cartridge in 1921. We are now getting very close to the concept except that the cartridge had a round-nosed rather than pointed bullet. A year later a modified 7.65 x 38 appeared which did have a pointed bullet. Swiss sources indicate that data from the tests of these rounds were passed to DWM in Germany, where they may have influenced later developments. Other pre-Second World War Swiss short-case ammunition designs included a different and rather mysterious 7.65 x 38 round for which unloaded components were made in some quantity, for an unknown destination, just before the war.

In Italy the Terni Model 1921 selective-fire carbine emerged: the cartridge was a 7.35 x 32 rimless round, a shortened and necked-out version of the standard 6.5 x 52, which fired a pointed 8.7 g (134.5 grain) bullet at a claimed 600 m/s (1,970 fps). In the early 1930s, the US Frankford Arsenal tested this rifle, or one very like it. Various other Italian experiments took place throughout the interwar years, but to no effect: the 7.35 x 51 round eventually selected was designed to be used in rebarrelled 6.5 mm weapons (they increased the calibre because it was cheaper to rebore existing worn-out barrels instead of buying new ones), but it was at least loaded to quite modest levels in recognition of the fact that long range was not required. In 1925 Kynoch of the UK proposed a "7 mm light automatic rifle cartridge" intended for BSA. The factory drawing shows a bottle-necked case with a length of 41 mm and a round-nosed bullet. It is not clear whether the cartridge or gun were ever built. In Russia, Federov continued to argue for the adoption of a smaller cartridge than the 7.62 x 54R. In the late 1920s he recommended adoption of the 6.5 mm calibre "if not even smaller" and a rimless or semi-rimmed case with a length shortened by about 20 % (to 40 mm). His ideas were supported in 1930 by V.E. Markevich, of the Red Army's Weapons Scientific and Research Range, who pointed out that an ideal

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cartridge already existed in the .25" Remington hunting round! The bigger brother based on the same case, the .30" Remington, was used much later as the starting point for the development of the 6.8 mm Remington Special Purpose Cartridge. In the early 1930s Denmark made limited numbers of the delayed-blowback Weibel (or Danrif) M/32 assault rifle in a 7 x 44 calibre. From this rifle, the 8 gram (123 grain) bullet reportedly achieved a muzzle velocity of 750 m/sec (2,460 fps) for an ME of 2,250 J. In 1939 a light automatic weapon was advertised in Greece in 7.92 x 36 calibre, the cartridge apparently being based on a shortened and necked-out 6.5 mm Mannlicher case. In fact, despite the evidence that most small-arms engagements during WW1 were at short range, armies showed more interest in new FP rifle/MG rounds. The Japanese Army began to replace their 6.5 x 50SR cartridge with a new 7.7 x 58 calibre, although they never completed the changeover. The Italians were similarly caught at the start of WW2 part-way through a change from their 6.5 x 52 Mannlicher-Carcano rifle to a 7.35 x 51 calibre. This happened for several reasons. One was that long-range MG fire was considered essential: the first Japanese Army 7.7 mm round was only available in MGs (the first 7.7 mm rifles only emerging about a decade later), and other powerful MG rounds (e.g. the 8 mm Breda, 8 mm Bofors and 8 mm Solothurn) were introduced during this period.

Swiss 7.65 x 35, Swiss 7.65 x 38 with bullet, .276 Pedersen (7 x 51), 7.35 x 52 Italian

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For the most part, the introduction of rifles in the new MG calibres seems to have been to simplify ammunition supply arrangements, rather than because the smaller calibre rifles were felt to be ineffective. Finally, the need for a full-auto rifle (and therefore lower-powered ammunition with less recoil) was not recognised and probably generally resisted, on the grounds of economy (automatic rifles being much more expensive and requiring more maintenance than bolt-action ones), and also the fear that soldiers would just spray ammunition around at a great rate, causing increased cost and supply problems (this latter concern was, of course, fully justified, but was addressed by improving supply arrangements). So even the one nation wealthy enough to afford an automatic rifle the USA restricted the M1 Garand to semi-auto fire, and FP rounds biased towards MG use prevailed. There had been some efforts towards considering intermediate calibres, with the US Ordnance Board sponsoring comparative trials in the early 1930s of the effectiveness of different rifle cartridges using anaesthetised pigs and goats to assess wounding effectiveness. They concentrated on a .256" (6.5 mm), a .276" and the existing .30". The .256" (8 g at 820 m/s, for 2,700 J - much more powerful than the .25" Remington) most impressed the testers, but the Board chose the .276" Pedersen (7 x 51) developing 2,400 J (similar in power to the 6.5 mm Arisaka, the later 7 x 43 British and the modern 6.8 mm Remington). However, the army was still thinking in terms of long-range semi-automatic fire, a mindset which did not change until the 1960s. The .276" cartridge was rejected in 1932, partly for cost reasons but also because it did not offer sufficient long-range performance. World War 2 - the Assault Rifle Emerges In the run-up to World War 2, the focus switches to Germany. In the aftermath of the Great War a Hauptmann Piderit of the German Rifle Testing Commission had advocated a short-cased cartridge and a suitable rifle to fire it, but his was a lone voice. It wasn't until 1927 that DWM (actually, the "Berlin-Karlsruher Industriewerke A.G." as DWM was known between 1922 and 1936) carried out the first tests of short-cased cartridges, possibly as a result of the data they had received about the Swiss rounds, but these had no direct result. It wasn't until the mid-1930s that serious work got underway, and over the next decade no fewer than five German companies were involved in developing short-cased cartridges suitable for assault rifles: Geco, DWM, RWS, Rheinmetall-Borsig and Polte. Geco was the first in the field, co-operating with the gun company Vollmer-Werke Maschinenfabrik to produce the Vollmer SL Model 35 self-loading carbine in a nominal 7.75 x 40 calibre (the calibre was actually 7.9 mm, with a bullet 8.05 mm in diameter). This was officially tested with good results, but led to no orders. In 1942 Geco produced a new cartridge also intended for a Vollmer carbine, the 7 x 45SR. This used a wider case and was far more powerful, with a muzzle velocity of 1,000 m/s. Another cartridge, measuring 7.9 x 33.5, was designed at Geco and attributed to H.G. Winter, a director of the firm, but the date and the gun for which it was intended are not known.

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DWM designed a 7 x 39 cartridge in the mid-1930s, for which a Walther self-loading carbine was reportedly made. It was appreciably more powerful than the later 7.9 x 33 Kurz. However, the interest of the Heereswaffenamt (HWA) was by then focused on Polte developments, so the DWM round also failed to progress. RWS produced several short-cased rifle rounds in the 1930s, including an 8 x 45, 8 x 46 and 7 x 46, but these developments were taken no further. Rheinmetall-Borsig were involved in a number of prewar experiments concerning 7 mm rounds in various case lengths, some of them very long, probably for high-velocity aircraft gun projects. One drawing has been found of a 7 x 36 cartridge which would obviously have been suitable for assault rifles, but there is no evidence that it was made. The design work may have been done by Polte on behalf of Rheinmetall-Borsig. This brings us to Polte Patronenfabrik of Magdeburg, who made by far the most significant contribution. The HWA awarded them a contract, probably in 1938, for the development of a short-cased infantry cartridge. This resulted in several different designs of cartridge; 7.9 x 45, 7.9 x 30, two different 7.9 x 33 and a 7 x 45, all by 1940. In all of these, Polte retained the base diameter of the standard 7.9 x 57 rifle/MG round, and in all but the 7 mm the same calibre as well. This kept production costs to a minimum and no doubt helped to account for the success of their proposals. The final 7.9 x 33 design (which had less case taper than the first or "transitional" effort) was approved in December 1940, the only subsequent change being to the angle of the extractor groove, which was altered from 45 to 60 degrees in May 1942. The selective-fire MKb42(H) by Haenel and the MKb42(W) by Walther were designed around the new cartridge and produced in some numbers for field testing. This led to the selection of the Haenel as the MP43/44 (later renamed StG 44 for Sturmgewehr or assault rifle the origin of the name).

The author shooting the MKb42(W) at MoD Defence Academy, Shrivenham

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The StG 44

This was what the Army wanted to support the most important weapon in the squad the MG 42 GPMGs and it was produced and used in quantity, with nearly half a million made. However, the end of the war stopped the direct line of development of this highly significant weapon. At the same time as the German work was reaching its conclusion, the USA was developing the .30 M1 Carbine, a light rifle chambered for a new 7.62 x 33 straight-cased round based on the old .32" Winchester SL commercial case. This was not intended as an assault rifle but as what would now be called a "personal defence weapon" (PDW) for troops who would not normally carry a rifle. However, its handiness meant that some front-line troops carried it in preference to the much bigger and heavier .30 M1 Garand rifle. The M2 version of the Carbine introduced selective fire and was close to the specification of an assault rifle, but the cartridge with its round-nosed bullet was really too small and weak (1,200 J) to reach out to 300 m (330 yards), considered the desirable effective range as some 90% of fire-fights took place within that distance. Attention now switches back to the USSR. The key date was 15th July 1943 when a meeting was held of the Technical Council of the People's Commissariat for Armament (NKV). They met to consider "New foreign weapons firing lower-powered rounds" and studied examples of both the US .30 M1 Carbine supplied by the USA, and the German MKb 42 (H) in 7.9 x 33 which had been captured while undergoing troop trials. The meeting concluded that the new German gun and cartridge were important developments and decided that a new reduced-power round must be designed for the Soviet Army. Responsibility for this was handed over to the OKB-44 design bureau, which produced the first prototype of what became the 7.62 mm M1943 round only a month later, with the first batch of ammunition loaded with flat-based lead-cored bullets being range-tested that December. This kept the same calibre as the 7.62 x 54R rifle/MG round for production convenience, but adopted a new case which was slimmer than that used by the 7.92 x 33. A pilot series-production run began in March 1944, and before the end of the war the round was combat-tested in prototypes of the Degtyarov RPD light machine gun and Simonov SKS semi-automatic carbine.

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At that time the case had a length of 41 mm, but development work continued, resulting in a boat-tailed bullet shape being adopted and the lead core being replaced with mild steel. The case neck was reduced to the final 38.7 mm to keep the overall round length the same despite the longer bullets. The story was not yet over. Federov, the old pioneer and true father of the intermediate calibre selective-fire rifle concept, now "Doctor of Services, Professor Lt. General (Technical Engineering Branch) V.G. Federov" and serving as a senior member of the Technical Council of the NKV, continued to argue for a smaller-calibre cartridge. As a result, between 1946 and 1948 several different rounds were made and tested in 6.75 mm as well as 7.62 mm calibre. Despite this, the 7.62 x 39 M1943 cartridge was finally selected in 1948, when the AK-47 was already undergoing pre-production troop trials. One of the reasons for retaining the 7.62 mm calibre was said to be that the Soviet manufacturing plants did not at that time have the equipment to mass-produce smaller-calibre ammunition and gun barrels with the necessary precision. Some sources claim that the 7.62 x 39 was no more than a copy of a German Geco cartridge for the Vollmer M 35 carbine, designed in 1934/35 by the aforementioned H.G. Winter. However, as we have seen, the cartridges designed for that gun were quite different, having larger case diameters. The round often cited as the model for the M1943 is the 7.62 x 38.5 "Mittelpatrone", but the diameter of that case is also larger than the M1943's and, according to Dynamit Nobel (Geco's postwar parent company), it dates from 1960; it appears that it was in fact inspired by the M1943, not the other way round. There is therefore no known German cartridge of which the 7.62 x 39 M1943 could have been a copy. The authors of a Russian history of the M1943, who had access to Soviet archives, were unable to find reliable information as to whether the USSR had any earlier knowledge of the development of intermediate rounds in the West. After the Battle reviewing the experience of World War 2 As the war drew to a close, the victors began to absorb the lessons and consider what kind of small arms would be needed in the future. The USSR was alone in simply continuing their late-war developments based on the 7.62 mm M1943 cartridge, the next assault rifle to enter service after the StG 44 being the Kalashnikov AK in this calibre. There is still some sensitivity about the connection between the AK and the StG 44, but two things are clear; despite the apparent similarity, the AK was not a direct copy as it uses a quite different operating mechanism, but on the other hand Kalashnikov and his team must have known about the StG 44 (tens of thousands were captured and examples would certainly have been provided to Soviet small-arms design teams) and it is difficult to believe that they were not influenced by it, even if only to take it as a starting point for improvement. There is no evidence that Kalshnikov received any assistance from German engineers who were in the USSR after WW2.

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It should perhaps be noted that the term "AK-47" was applied by the Russians only to the pre-production version of the gun, of which a few hundred were made for troop trials between 1947 and 1949. Modifications were then made to the design before it was formally adopted as the AK (Avtomat Kalashnikova, or automatic [rifle] by Kalashnikov). In 1959 the AK was replaced in production by the AKM, which was lighter and cheaper due to the replacement of the machined receiver by one of stamped steel. However, both AK and AKM have always been popularly if inaccurately known in the West as the AK-47.

WW2 and after: .30 M1 Carbine, 9 x 35 Lahti, 9 x 40 Lilja, 7.92 x 33 Kurz, 7.62 x 39

AK, 7.5 x 45 Czech, 7.62 x 45 Czech, 7 x 36 Madsen/Otterup, 7.65 x 38 French, 7.5 x 43 French CRBA, 7.62 x 38 Swiss, 7.92 x 40 CETME

The AK / AKM and its ammunition (also used in the RPD light MG) so dominated the assault rifle field until the late 1960s that it is sometimes forgotten that there were other developments, one of which saw service. This was the Czech vz52 rifle chambered for their 7.62 x 45 (after earlier experiments with a 7.5 x 45), a superior cartridge to the AK's in terms of range, but it was soon replaced by the vz52/57 (chambered for the 7.62 x 39) in the interests of commonality with the rest of the Warsaw Pact. The vz52 was only semi-auto, but the Czechs were working on the selective fire vz58 when the changeover to the Russian calibre took place.

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Other nations also experimented with short-case FCAR rounds, particularly the French and the Swiss. Cartridges such as the Swiss 7.62 x 38, the French 7.65 mm Model 48 (7.92 x 35 - the French also experimented with calibres up to 9 mm) and the 7.5 x 43 CRBA of the late 1950s, plus the Danish 7 x 36 Madsen or Otterup, were all unsuccessful contenders during the early postwar years. Also falling loosely into this category were late-WW2 efforts in Finland, producing such cartridges as the bottlenecked 9 x 35 Lahti (in the AL43 - a modified SMG design) and the straight-cased 9 x 40 Lilja, but these had light, round-nosed bullets indicating their SMG origin. A 7.62 x 35 version of the Lahti, with a pointed bullet, was more promising but still not adopted. Developments in the UK and the USA were on a different track and deserve more individual attention, because they both rejected the c.300 m range assault rifle concept adopted by Germany and the USSR. One consequence of selecting such an assault rifle as the standard infantry weapon is that it must be supported in the squad by a longer-ranged weapon, usually a belt-fed LMG. As mentioned above, the USSR fielded the RPD in 7.62 x 39 calibre as the squad LMG but eventually realised that this was the wrong approach, and replaced it with the PKM in the old but powerful 7.62 x 54R calibre. Many other nations (particularly in NATO with regards to the 5.56 mm) also assumed that such assault rifle ammunition would be suitable for the squad LMG, but the test of combat has caused opinions to be revised. The approach taken, separately, by both the UK and to an even greater extent the USA, was to develop a general-purpose cartridge (GPC) which could be used in all section/squad weapons. This is not an easy trick to pull off since to replace the traditional FP cartridges such as the .30-06 and the 7.62 x 54R requires a long effective range, but to be suitable for a light, selective-fire carbine requires a low recoil. These two requirements are contradictory and require a careful balancing act between calibre, bullet weight and shape, and MV to get right. The British Small Arms Calibre Panel The UK approached the whole question of small-arms ammunition (SAA) design systematically, first defining General Staff Requirements (GSR), which laid down what the ammunition was expected to achieve, then establishing a panel to consider the optimum cartridge design. The GSR stated that "The object of research for the ideal SAA cartridge is to facilitate the design of the most efficient weapons and ammunition compatible with the minimum weight", and it contained the following key performance requirements: The ammunition is required for use in the following weapons: lightened rifle;

sniper's rifle; self-loading gun, light automatic gun, and medium machine gun (if practicable)1

Ammunition required for use at ranges from 0-800 yards (730 m), for all weapons up to but not including the MMG. If the ammunition can be made suitable for use with the MMG as well as with the other weapons, so much the better. This desideratum, however, must NOT influence the problem if it is liable to impose limitations on the design of the bullet, weight or charge (and therefore capacity of cartridge case) or other characteristics affecting the other weapons2

Ammunition types to include ball, tracer, incendiary, observing, and an A.P. load

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for use against vehicles carrying NOT MORE THAN 10 mm of armour, up to a range of 100 yards (90 m)3

The ball projectile should be effective against personnel in trenches protected by 20-24" (50-60 cm) of loose earth, 1-1 (25-37 mm) of unreinforced concrete, or their equivalent at 100 yards based on single-shot performance

Trajectory to be as flat as possible, particularly up to 600 yards (550 m) Accuracy when used in a sniper rifle: a five-round 3 inch (76 mm) group at 200

yards (180 m) The ideal to be aimed at is NO smoke and NO flash. Of these, smokelessness is

the more important. If flashlessness cannot be combined with smokelessness, it must be possible to eliminate the flash by the use of a flash eliminator of dimensions similar to that fitted to the No. 5 rifle4.

Notes: 1 The "lightened rifle" was presumably meant to be a Lee Enfield replacement, the "self-loading gun" would be a new type, the "light automatic gun" would be a Bren replacement and the "medium machine gun" would replace the water-cooled and tripod-mounted Vickers.

2 The Vickers MMG firing .303" Mk VIII streamlined ball ammunition had a maximum range in the region of 4,000 m, although about half that would have been the practical maximum against area targets; so it seems rather optimistic to expect a round optimised for up to 730 m in lightweight weapons to do the same job.

3 .303" AP with a hardened steel core was capable of penetrating 10-11 mm armour. 4 The No. 5 rifle was a short-barrelled .303" Lee Enfield, more popularly known as the "Jungle Carbine". The "flash eliminator" was a cone-shaped device similar to that fitted to the Bren (and to the 14.5 mm KPV HMG to this day), which might have been better described as a "flash hider". It had the incidental effect of increasing the already heavy recoil of the No. 5. The Small Arms Calibre Panel produced a report (popularly known as the Beeching Report) in March 1947 after studying how best to respond to the GSR. Their analysis consisted of an admirably concise eight pages of text, but many more pages of tables and diagrams in support of the arguments. They covered: 1. Bullets of calibre 0.25 to 0.33 inches (6.35 to 8.6 mm) of both flat-based and

streamline (boat-tailed) types, and different ball and AP core materials 2. Armour penetration against 4, 6, 8 and 10 mm homogenous armour at 0, 10, 20,

30 and 40 degrees angle of attack 3. Concrete penetration against 2 inch thick slabs, plus earth penetration data 4. Wounding and stopping power (inconclusive, due to lack of objective evidence) 5. Flatness of trajectory: a vertex height of 3.2 feet (975 mm) to 600 yards (550 m)

was assumed, the same as the 7.92 mm Mk 2z Besa ball 6. Internal ballistics: two chamber pressures representing the top and bottom of

current experience were considered; 25.2 tons and 19.2 tons per square inch (56,450 and 43,000 psi, or 390 and 300 MPa). Barrel life with different propellants was also assessed (of particular concern for the LMG)

7. Cartridge case shape was considered, in terms of volume, weight and length for a given capacity of brass case

8. Recoil energy: 12 ft/lb (16 J) was considered to be the practical limit for a single shot, but 8 ft/lb (10.8 J) for automatic fire (implying that an automatic rifle would have to weigh 50% more than a semi-auto firing the same ammunition).

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9. Accuracy: largely down to barrel wear, linked to the charge/weight ratio; which militates against small-calibre high-velocity rounds.

In the discussion section it was observed that the two key targets to meet were the flat trajectory and armour penetration once these were achieved, the other performance targets fell into place. The requirement to achieve a flat trajectory out to 600 yards could best be achieved by firing a light bullet at high velocity; this would be acceptable as penetration requirements were only specified at short range. This implicitly meant that the possibility of using the chosen ammunition in an MMG had been abandoned, as that would require a heavy bullet to retain energy at long range. It was also noted that "decreasing the calibre permits a smaller and lighter round and a lighter weapon for a given performance" but it was pointed out that there were limits to this, concerned with: barrel wear increasing as the calibre decreases, due to an increase in the charge/weight ratio; increased production difficulties; and it was "impossible to construct a rifle below a certain weight, about 5-6 lbs (2.5-2.7 kg)"; once this had been achieved, weapon weight could not be further decreased no matter how much the calibre was reduced by. After considering the performance of various options, the Panel came to the following conclusion concerning the calibre:

"If the full specification is adhered to, and tungsten carbide AP bullets are not permitted, the calibre should be about .27 inches (6.8 mm), but if the use of tungsten carbide is allowed or the armour performance clause is relaxed it would be an advantage to choose a lower calibre down to .250 (6.35 mm), the lowest calibre considered."

Perhaps the most interesting of the diagram pages can be found at the end of the report, in which many different cartridges in various calibres and sizes, and with various weight bullets, are listed. For the .27 inch (6.8 mm) calibre, the preferred bullet weight to achieve the targets was 100 grains (6.48 g), with the MV being 2,860 fps (872 m/s), giving an ME of 2,464 J. Interestingly, one different loading of the .27 was also included, of a 120 grain (7.78 g) bullet at 2,590 fps (789 m/s), for 2,422 J; this offered the potential of a longer effective range at the cost of a higher medium-range trajectory. Estimated round weights were 15.0 and 16.4 g respectively. At about the same time these conclusions emerged, a round which was evidently designed with this specification in mind appeared: the .270 British (6.8 x 46). This used a case of base diameter 11.2 mm (similar to the .276 Pedersen, 7.62 x 39, 6.5 mm Grendel, 7 x 46 UIAC and, last but far from least, the 264 and 277 USA). It was loaded with a 6.48 g (100 grain) bullet fired at 840 m/s (2,750 fps), for an ME of 2,286 J. This round showed that the cartridge calculations in the Panel report were somewhat optimistic; the ME was slightly less but the cartridge weight was significantly more the one example checked weighs a fraction under 18.0 g. The .270 was a general-purpose cartridge (GPC) for the squad/section in that its effective range of 800 yards was significantly better than the 7.92 x 33 or 7.62 x 39 and would address most of the needs of infantry combat. However, it did not cover all of the roles of SAA as it could not replace the .303" Vickers MMG which functioned

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as a heavy support weapon higher up in the infantry organisation; although given that the Vickers was eventually replaced by the 7.62 mm GPMG with a rather shorter range, the streamlined 120 grain loading of the .270" might have proved adequate for that purpose. While using two different loadings of the same cartridge has generally proved unsatisfactory (the Chinese being the latest to discover that with their 5.8 x 42 round), it would be less of a problem with the heavy load confined to belt-fed ammunition for the dedicated MG support platoon. The other solution would of course have been to relax the flat trajectory requirement a little by adopting the .270"/120 grain load as standard that could have been a true GPC. However, the General Staff Requirements, and therefore the Panel's assumptions and the resulting .270 British, were all abruptly abandoned in 1948 for something entirely different. Which brings us to the US developments. The US Army's .30 Light Rifle project and the NATO trials At the end of WW2, the US infantry squad had an advanced rifle (the semi-automatic .30 M1 Garand), a useful lightweight selective-fire carbine (the .30 M2 Carbine), a compact SMG (.45 M3) and a heavy automatic rifle (the .30 cal Browning Automatic Rifle, or BAR). The Garand and the BAR both used the .30-06 cartridge (7.62 x 63, developing 3,450 J muzzle energy), the .45 M3 used the same low-velocity ammunition as the Colt M1911A1 self-loading pistol, and the .30 Carbine used its own unique 7.62 x 33 straight-cased ammunition, developing just 1,200 J. The US Army was keen to reduce the number of weapons and cartridges, and wanted a lightweight, selective-fire rifle of .30" / 7.62 mm calibre to replace both the Garand and the Carbine. They also hoped that the "Light Rifle" could replace the BAR and the M3 SMG. The problem was that they also wanted a new all-purpose cartridge which, while shorter than the .30-06, retained a similar performance at long range for use in MMGs out to 2,000 yards (1,800 m). This was a far more ambitious target than the British had set for the .270, and therein lay a problem. Retaining the same calibre and long-range effectiveness meant that the new cartridge had to be just as powerful as the .30-06, which already generated heavy recoil. Making the rifle lighter would merely magnify that problem. It appears that Colonel Studler, who was in charge of the project, may have planned to tame the recoil by gun design measures such as a straight-line stock plus a large and sophisticated muzzle brake. However, the early prototypes with these characteristics were soon dropped in favour of what became the M14, which was very similar to the Garand except for being a little shorter and lighter and having a detachable magazine of larger capacity. Unsurprisingly, this proved uncontrollable in automatic fire so the auto switch was soon disabled for most users. This meant that in practice the M14 could only replace the Garand as it was too light to replace the BAR and too heavy, with too much recoil, to replace the Carbine and SMG. It could not be described as an "assault rifle". This might not have bothered anyone else except that NATO was formally established in 1949 and it was decided that it would be a worthy symbol of intent, as well as having obvious practical benefits, if the multitudinous rifle/LMG cartridges in service in the various NATO nations were replaced by one, common cartridge and preferably one, common rifle (the former was achieved, the latter was not). It was

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immediately clear that whatever the US Army chose would almost certainly become the new NATO cartridge, and that the US wanted a single, general-purpose round with a good long-range performance to replace the .30-06 in all existing weapons. This development torpedoed the British .270 which with its 100 grain bullet could not meet the long-range energy requirement. It is not known whether the proposed streamlined 120 grain loading of the .270 was considered; its sectional density would have been fractionally better than the 7.62 M80, with a better form factor being easily achieved given the more slender proportions, so the ballistic coefficient should have been superior. Instead, the British designed an alternative round which would have a much heavier bullet to retain its energy at long range (ultimately of 140 grains or 9.1 g, although 130 grain / 8.4 g bullets were tried initially), paid for by a significant reduction in muzzle velocity to keep the recoil in check. Enter the .276 British, quickly renamed .280 to avoid confusion with earlier rounds, and shortly after that renamed .280/30 when the base of the case was slightly altered to match that of the .30-06 and .30 Light Rifle rounds, to make conversion easier. In metric terms it is known as the 7 x 43. The case is shorter and fatter than the .270's, presumably in order to leave more room for the longer bullet ogive without exceeding the same overall cartridge length.

The British had also designed a new rifle for whatever their new cartridge might be: the EM-2 (shown above). This was one of the first selective-fire rifles to adopt the bullpup configuration, with the action and magazine in the rear part of the stock behind the pistol grip, thereby resulting in a considerable reduction in the overall length of the rifle for any given barrel length. This compact layout combined with the relatively low recoil of the cartridge made it feasible as a replacement for the 9 mm Sten SMG as well as the Lee-Enfield rifle and it therefore did the same job as an "assault rifle", albeit one with a remarkable long-range performance. A GPMG based on the Bren mechanism but with belt feed, the TADEN, was also developed to use this round and replace both the Bren and (at least partly) the Vickers MMG.

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7.92 mm EM-1 Roman Korsak LMG, which predated the 7 x 43 EM-1 and EM-2 It is worth noting that there is some confusion over the EM-1, since two different weapons were assigned the same designation: the first was a full-powered (7.92 x 57) bullpup LMG by Roman Korsak, a Pole working in England; the second EM-1 was a rival to the EM-2 in the same 7 x 43 calibre, which had a similar bullpup configuration but with a different action and was made from stampings and pressings rather than machined.

TADEN GPMG

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The EM-2 (shown above being fired by the author at Shrivenham) and its .280/30 cartridge were submitted for comparative testing in the competition to select a new standard NATO rifle/MG cartridge. The initial results were promising: the 7 x 43 was regarded by the US Army's testers at Fort Benning as a better basis for development than the US .30 cal round with which it was competing, due to its combination of long range and moderate recoil, and other NATO countries (Canada and Belgium, at least, who both made ammunition) were very interested in the concept. However, the US Army leadership was unconvinced, arguing that it was not powerful enough, the modest muzzle velocity giving it a higher trajectory at medium range. The British and Belgians made great efforts to meet these objections by steadily uprating its performance. The first effort was to step up the MV from 736 m/s (2,415 fps) to 770 m/s (2,525 fps), followed by seating the bullet less deeply to make more room for propellant (the 7 mm Optimum or 'S'). Longer cases were also tried: a UK-only High Velocity variant with a 49.5 mm case length and an MV of about 838 m/s (2,750 fps); then the 7 mm Compromise (the new US .30 cal case necked-down, with a length of 51 mm) with an MV of about 850 m/s (2,800 fps); then the 7 mm Second Optimum or Medium (the Belgian 7 x 49 with an MV of 840 m/s, which was the only one of the series to see service - with Venezuela in the FN FAL rifle). In all of these, the bullet remained the same weight at 9.1 g. The EM-2 plus 7 x 43 combination appears to have achieved all that was asked of it, and in 1951, while the above experiments were going on, the cartridge was briefly adopted by the UK as the '7 mm Mk 1Z' (with the 43 mm case length and a 9.1 g bullet at 777 m/s - 140 grains at 2,550 fps, for an ME of 2,747 J), at the same time as the EM-2 was adopted as the 'Rifle, No.9 Mk 1'. However, it faced insurmountable political obstacles. The Americans insisted on NATO adopting its new FP .30 cal cartridge - which meant by definition that it could not be used in an assault rifle. A change of government resulted in the British giving way and cancelling the EM-2 and

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its cartridge in favour of the FN FAL in what was now designated the 7.62 x 51 NATO, after initial work on a 7.62 x 48 T65 prototype. Apart from being half an inch shorter than the .30-06 cartridge, this represented no progress over that fifty-year old design. The EM-2 was stretched to fire the new NATO round, but the heavy recoil destroyed the balance of the weapon's characteristics and it went no further.

.30-06, .270 British, .280/30 (7 x 43), 7 x 49 Medium, 7 x 49.5 HV, .30 T65 (7.62 x

48), 7.62 x 51 NATO One final contender worth its own paragraph is the Spanish 7.92 x 40 CETME Model 53. The ammunition was designed by Dr Gunther Voss, a German ballistician working for CETME. He wanted to combine a good long-range performance with light recoil, which he achieved by using a 6.9 g (106.5 grain) bullet made from solid aluminium alloy except for the copper sleeve around most of its length, which compensated for its light weight by being highly streamlined. As a result, it achieved a ballistic performance comparable with the 7.62 x 51 (MV was 800 m/s from a carbine-length barrel of 435 mm) with a significant reduction in ammunition weight and an even bigger reduction in recoil. The irony is that both the 7.92 mm CETME Model 53 and the 7 mm EM-2 came much closer than the M14 and its 7.62 mm ammunition to meeting the US Army's

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originally stated aim of adopting a lightweight selective-fire rifle which could replace the M1 Garand rifle, the M2 Carbine, the BAR and the M3 SMG. NATO had effectively rejected the assault rifle concept for a whole generation of weapons, at the same time as Kalashnikov's rifle was achieving worldwide success. The Small Calibre High Velocity (SCHV) Revolution Small-calibre rifle cartridges were in use or under development for military purposes from very early days. The 6 mm Lee of 1895 is probably the best known as it was briefly adopted by the USN, but the curious 5.2 mm Mondragon of 1894 was also made (the odd shape resulting from an internal piston to give the bullet an initial kick up the barrel) and the 5 mm Sturtevant was being developed towards the end of WW1. At that time the available propellants were not suited to getting the best from such rounds: despite their large cases, performance was modest.

From left to right: 7.62x51 for scale, 6mm Lee, 5.2mm Mondragon, 5mm Sturtevant

American experiments were made in the 1950s with a range of smaller calibres, such as the .22 APG (designed for use in a modified M2 Carbine), .22/30 NATO, the .25/30 NATO (6.35 x 51) and the .27 NATO (6.85 x 51), but these led to nothing.

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Frustratingly for the assault rifle supporters, the US Army realised after initial experience in Vietnam that they had made a mistake and cancelled further production of the 7.62 mm M14 rifle (which had anyway experienced serious production quality problems). Inspired by experimental work which showed the efficiency of small-calibre rifles, the USA went to the other extreme in adopting the M16 rifle and its relatively tiny .223 (5.56 x 45) cartridge (after some competition from the .224 Winchester and two different .25" Winchesters: 6.35 x 48 and 6.35 x 53). The 5.56 was developed from a Remington commercial small-game hunting round and had an ME of only 1,690 J. This rather missed the point of the early SCHV testing which involved more powerful cartridges with much higher ME. The US adoption was actually only intended to be an interim purchase pending the perfecting of the SPIW flechette rifle (see below) but as this never happened, the 5.56 x 45 became the US Army's standard rifle cartridge by default. Much controversy arose about its effectiveness in stopping a determined enemy, but what was obvious was that the long-range performance of the little bullet (designated M193) was poor. It was adequate at up to 300 m when fired from a full-length (20" / 508 mm) barrel, but more like 200 m in the short-barrelled carbines which gradually began to appear.

SCHV rounds: .22 APG, .22/30 Homologous (5.56 x 51), .25/30 Homologous (6.35 x 51), .27/30 Homologous (6.86 x 51), .224 Winchester E2, .25 Win FA-T 116 (6.35 x 48), .25 Win Duplex FA-T 127 (6.35 x 53), 5.56 x 45 M855, 5.45 x 39 AK74, 5.8 x 42

Chinese A wide range of SCHV experimentals followed, many even smaller and/or less powerful than the 5.56 x 45. Several used 5.56 x 45 cases necked down to smaller calibres; one of these, the British 4.85 mm (actually a 5 mm) was entered in the late 1970s NATO trials). Others used purpose-designed ammunition such as the 4.6 x 36 HK for the HK36 rifle (not to be confused with the current 4.6 x 30 for the HK MP7 PDW, nor with the current HK G36 5.56 mm rifle), which featured a 'spoon tip' to the bullet to encourage tumbling on impact. One disadvantage of such small calibres is their capillary effect: once water gets into the barrel, it tends to stay there, affecting chamber pressures on firing.

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Some new rounds depended on other types of clever bullet design to achieve their performance. We have already seen how the CETME 7.92 x 40 achieved this; a similar if less radical SCHV example is the US 5.56 x 38 FABRL (Frankford Arsenal / Ballistic Research Laboratory), which was based on a lightweight (37 grains / 2.4 g) but aerodynamic bullet which matched the ballistic coefficient of the 5.56 mm M193. The light bullet required much less propellant to accelerate it to the same muzzle velocity as the M193, so the cartridge case could be shorter (leaving room for a longer bullet ogive), and the chamber pressure was low enough to make an aluminium case feasible, reducing the weight further. The net result was a round which matched the velocity and trajectory of the M193 while weighing half as much and generating less than half of the free recoil energy. Furthermore, it needed no special weapons: existing M16 rifles could easily be adapted to fire it, with little more than a barrel change. However, as with the CETME round, such cleverness went unrewarded.

Experimental cartridges under 6 mm: FN 5.56 x 45 APDS, .12 US (3 x 47), 3.5 x 50 FN, 4.3 x 45 German, .17 US (4.3 x 46), 4.6 x 36 HK 36/CETME (with spoon-tip bullet), 4.85 x 49 British, 5.56 x 38 FABRL, 5.6 x 48 Eiger By the time the next competition for a new NATO rifle cartridge was held in the late 1970s, the 5.56 mm was in use throughout the US armed forces so was duly adopted, but in a new Belgian SS109 loading (M855 being the US version). This has a heavier bullet at a lower MV than the M193 and thereby achieves a better long-range performance and penetration although the consistency of its terminal effectiveness on human targets has been even more critically questioned. As a relatively short-ranged assault rifle round, the 5.56 mm was adequate, but users pushed the little cartridge into roles it was not designed for and performed badly, such as in a medium-range belt-fed machine gun (it should be remembered that the NATO competition was for a round to supplement, not replace, the 7.62 x 51). The

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USA has continued to develop improved 5.56 mm ammunition to squeeze the most out of the little cartridge, recently adopting the lead-free M855A1 Enhanced Performance Round and the USMC's MK318 Mod 0. The Russians were inspired by the 5.56 mm to develop a new 5.45 x 39 cartridge for their next-generation rifle, the AK74. This is a bit less powerful than the 5.56 mm NATO although the long-nosed bullet does have an exceptionally good aerodynamic form giving it a surprisingly good performance at long range. Despite this, the Russians did not make the mistake of expecting too much from their assault rifle ammunition: they have retained the old, full-power 7.62 x 54R round in their squad light machine gun, the lightweight belt-fed PKM. More recently, the Chinese have introduced a 5.8 x 42 calibre for assault rifles and LMGs. The ballistics are little different from the 5.56 mm, although it is claimed that the 5.8 mm outperforms it, with penetration superior to the SS109, a flatter trajectory, and a higher retained velocity and energy downrange. The differences are only marginal, however, as the standard rifle round is only loaded to 41,500 psi (286 MPa) chamber pressure, compared with 55,000-62,000 for the 5.56 x 45 (379-428 MPa). Furthermore, the emphasis in the bullet design has been the penetration of body armour at some cost in effectiveness against soft targets; its hardened steel core will punch through 10 mm armour plate at 300 m, which is in the same class as steel-cored 5.56 mm AP rounds. A heavier loading of the 5.8 x 42 was also developed, for use in the GMPG and sniper rifles, but this use of two separate loadings for different weapons has predictably proved inconvenient, with the most recent development being the introduction of a new, universal loading (designated DPB-10), intended to replace the earlier versions. This has a 4.6 g bullet at 915 m/s (71 grains at 3,000 fps). The Chinese made the same mistake as many NATO nations in regarding their little assault rifle cartridge as being able to replace the FP 7.62 x 54R in MGs as well as the 7.62 x 39; weapons in the older calibre remain in service. Exotica 1: The SPIW At one time great hopes were placed in flechette technology (in principle, a scaled-down APFSDS tank gun round - APersFSDS?) to achieve an extremely short flight time and flat trajectory resulting from MVs of around 1,200-1,500 m/s (3,900-4,900 fps). This gives such weapons an almost ray-gun like performance, with allowances for range, wind-drift and target movement being hardly needed at normal battle ranges. This was first seriously proposed in the American Special Purpose Infantry Weapon (SPIW) project which began in the late 1950s, in which several manufacturers produced weapons using basically similar ammunition firing a 1.8 mm diameter dart with a plastic "puller" sabot filling the case mouth. The cartridge cases went through various evolutions (some of them shown below) and AAI's XM645 included primer-actuated unlocking: a large piston primer was designed to be moved backwards by the chamber pressure (an idea previously used in US experiments in the 1930s).

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Experimental US flechette rounds: 5.56 x 45 for scale, sectioned 5.6 x 44 XM216, XM216 (Springfield/Frankford, second generation), 5.6 x 44 XM144

(Springfield/Frankford, first generation), 5.6 x 53B XM110 (AAI first generation), 5.6 x 57B XM645 (AAI second generation) - all part of the SPIW programme. .330 Amron

Aerojet, 9.53 x 76R (both multiple flechettes) All manner of rifles from various manufacturers were developed to fire this ammunition, including traditional-looking wood-stocked ones, bullpups, space-age designs and even multi-barrel guns, some with drum magazines. There were also several attempts at a multi-flechette cartridge; one example being the .330" Amron Aerojet, another being the 9.53 x 76R, both of which contained three flechettes within their light-alloy cases. Accuracy was not as good as conventional rifles, however, and the cost of the ammunition was very high. While the penetration of armour was excellent, doubts were raised about the terminal effectiveness against unprotected targets and, to cap it all, the dust created by the disintegrating sabots turned out to have health risks. Attempting to achieve everything in one weapon by building in a multi-shot grenade launcher didn't help. The SPIW project faded out, eventually closing down in the early 1970s and leaving the "temporary" 5.56 x 45 with the accidental prize of becoming the USA's, and subsequently NATO's, new rifle/LMG calibre.

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Exotica 2 Multiballs and new cartridge shapes Other exotic experiments have proceeded in different directions, with different aims in mind. Some attempts have been made to improve the hit probability of conventional cartridges with multi-ball loadings, using two (duplex) or three (triplex) lightweight bullets stacked on top of each other. The .25 Winchester Duplex has already been mentioned, but another the US 7.62 x 51 M198 Duplex was actually accepted for service, and saw some use in Vietnam. A "salvo-squeezebore" (firing several stacked conical projectiles which were squeezed down to a smaller calibre by a muzzle attachment) was developed for the .50" BMG, and a version in 7.62 x 51 NATO was also tested but with unsatisfactory results. 7.62 mm APDS loadings have also been tried, and one of them has seen service with the Swedish Army as a sniper round.

Special loadings of service rounds: 7.62 x 51 M198 Duplex, .30'06 triplex, 7.62 x 51

salvo-squeezebore, 7.62 x 51 SLAP (Saboted Light Armor Penetrator) APDS

Other experiments have looked at different cartridge types to suit novel gun designs. Perhaps the most bizarre was the US "folded" ammunition, stemming from a desire to make the cartridge as short as possible to speed up the firing cycle. These were made in many calibres, from 5.56 mm to 30 mm. Another try was the Hughes Lockless (made in calibres up to 40 mm) which concealed the bullet within a flat, rectangular plastic case. This was designed to slot sideways into a simple gun action. Other oddities were the Belgian Schirnecker rounds of various sizes which fired saboted bullets from straight steel cases, and the 9/4 mm Kaltmann in which the plastic cartridge case was expected to follow the bullet down the barrel.

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Exotic attempts: 5.56 x 45 with lightweight Monad bullet, 4.5 mm Schirnecker, 9/4

mm Kaltmann (development round, with part-metal case), 5.56 mm Folded, 5.56 mm Hughes Lockless, 5.56 mm US caseless, 6 mm Voere caseless, early HK G11 4.7 x

21 rounds, final G11 4.7 x 33 The closest to adoption of all of the exotics was the caseless cartridge, in the form of the Heckler & Koch G11 rifle. It was actually about to be adopted by the German Army to replace the 7.62 mm G3 (Germany never having adopted the 5.56 mm NATO) when the Cold War ended and the Berlin Wall came down. Military re-equipment spending promptly halted. H&K were financially ruined by the cancellation of the G11 and temporarily fell into the hands of Royal Ordnance, where they earned their keep by sorting out the long-running problems of the British Army's SA80 rifle, but that's another story. In 2002, HK were taken back into German ownership. Caseless 5.56 mm rounds had also been experimentally developed around 1970 in the USA, and the Austrian firm of Voere even managed to sell some commercial caseless rifles in various calibres. Caseless ammunition has obvious benefits. It is much lighter and more compact (no metal case plus compressed propellant), and it is unnecessary to arrange for the extraction and ejection of the fired case (one of the main sources of weapon jams). The disadvantages are that: it is much more vulnerable to damage (which H&K got around to some extent by supplying the ammunition in sealed plastic see-through packs which clipped directly to the gun); sealing the breech against gas escape is more difficult; and the propellant is more likely to "cook-off" in a hot chamber, a problem exacerbated by the fact that a brass cartridge case transports some heat from the gun. Despite this, H&K (or rather Dynamit Nobel) developed a new heat-resistant kind of propellant, although at great cost. The most recent effort to use exotic technologies, the US Army's LSAT programme (described below), has explored caseless ammunition based on Dynamit Nobel's work, but found plastic-cased ammunition easier to work with.

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Exotica 3 - The ACR programme Flechette weapons were revived by two of the competitors in the Advanced Combat Rifle (ACR) contest of the late 1980s. This contest was intended to improve the poor hit probability achieved by average soldiers in the stress of battle, which using the M16 was only guaranteed (pH = 1.0) at up to 45 m, and dropped to a pH of 0.1 (one shot in ten) by 220 m. The theory was that firing three slightly dispersed shots in quick succession should enable the pH to be doubled, and several different weapon concepts were prepared.

The ACR rounds: Colt 5.56mm Duplex, AAI 5.56mm flechette, Steyr flechette, HK

4.7mm G11

The four ACR contenders shown above: HK G11 (foreground), Steyr (top left), Colt

(upper right), AAI (middle right)

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The four ACR contenders (from top to bottom): Colt, AAI ,Steyr, HK G11.

Photos taken at MoD Defence Academy, Shrivenham

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The G11 had a rather complex mechanism... The Colt ACR contender was simply an improved M16A2 firing a duplex cartridge, and H&K submitted the caseless G11 described above, while AAI and the futuristic Steyr offered weapons firing flechette rounds, the Steyr ammunition being plastic-cased. Although all of the weapons apparently performed well and did increase the hit probability, none of them managed to double it, so this once again proved a dead end.

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More Conventional Experimentals Despite the domination of the 5.56 mm NATO round (in much of the world) and the Kalashnikov family (in the rest), experiments with new, conventional ammunition concepts have continued. An instructive series of experiments took place in the UK in the late 1960s, when a thorough attempt was made to design an ideal military rifle round. This started with calculations of the bullet energy required to inflict a disabling wound on soldiers with various levels of protection. The energy varied depending on the calibre, as a larger calibre required more energy to push it through armour. For example, it was calculated that while a 7.62 mm bullet would need 700 J to penetrate contemporary helmets and body armour, a 7 mm would require 650 J, a 6.25 mm 580 J, a 5.5 mm 500 J and a 4.5 mm 320 J (this last figure should probably be 420 J). These figures applied at the target; muzzle energies would clearly have to be much higher, depending on the required range and the ballistic characteristics of the bullet. A range of "optimum solutions" for ballistics at different calibres was produced. These resulted in MEs ranging from 825 J in 4.5 mm to 2,470 J in 7 mm. More work led to a preferred solution; a 6.25 mm calibre with a bullet of 6.48 g at 817 m/s (100 grains at 2,680 fps), for an ME of 2,160 J. The old 7 mm EM-2 case was necked down to 6.25 mm for live firing experiments, although had the calibre been adopted a longer and slimmer case would have been used. Tests revealed that the 6.25 mm cartridge matched the 7.62 mm NATO in penetration out to 600 m and remained effective for a considerably longer distance, while producing recoil closer to the 5.56 mm. As related in The .256 British1, at much the same time, the US Army was looking to develop a new squad automatic weapon (SAW). The 7.62 mm was too heavy but the 5.56 mm didn't have a sufficiently long range, so a 6 x 45 round with a heavy, aerodynamic bullet was developed. This proved satisfactory but was not adopted because of concerns about putting a multiplicity of calibres into service. A light-alloy cased version of this round was also produced, with the length extended to 50 mm to make up for loss in capacity caused by the need to line the inside of the case with fire-resistant material (aluminium alloy having a tendency to catch fire). The Russians in the 1990s also unsuccessfully developed various new 6 mm cartridges under the "Unified" programme, but these were considerably larger and more powerful than the 5.45 mm, being intended to replace the 7.62 x 54R. The Swiss experimented with at least two cartridges in the late 1970s before adopting the 5.56 mm NATO; the 5.6 x 48 Eiger and 6.45 x 48 GP 80. The 5.6 mm fired a 3.7 g bullet at 1,050 m/s for 2,040 J (considerably more than the 5.56 mm NATO) while the later 6.45 mm managed to propel its 6.3 g bullet at 900 m/s for 2,550 J. Both rounds were based on the 12 mm-wide 7.62 x 51 NATO case and were therefore considerably larger than most other intermediate rounds. With the benefit of hindsight, a heavier bullet at a more moderate velocity might have provided a better loading for the 6.45 mm, possibly producing a "general-purpose cartridge" (GPC) which could replace the old FP cartridge. As it was, the old 7.5 x 55 was retained in

1 http://quarryhs.co.uk/256brit.htm

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service alongside the 5.56 x 45.

Some experiments since the 1970s: 5.56 x 45 for scale, 6.5 x 43 German, 6.25 x 43 British, 6 x 45 SAW, 6 x 50 SAW aluminium-cased, 6 x 49 Russian Unified, 6.45 x 48

Swiss GP80 Germany also produced an interesting-looking 6.5 x 43 round in the early 1960s which seemed to have had some potential as a GPC, but this was only used for ballistic testing. Various developments in the 21st century have aimed to improve on the performance of the 5.56 x 45 while still keeping the ammunition short enough to function in modified 5.56 mm rifles. One is the 6.8 x 43 Remington SPC (Special Purpose Cartridge) which in its standard ball loading fires a 115 grain bullet at around 2,525 fps from a 16 inch (406 mm) barrel (7.45 g at 770 m/s = 2,200 J). The cartridge case is based on the old .30 Remington commercial round, with a diameter of 10.6 mm, intermediate between the 5.56 x 45 (9.5 mm) and the 7.62 x 51 (12 mm). Overall length is kept within the 57 mm limit to fit in 5.56 mm actions, which limits the length of the bullets which can be loaded, blunting their long-range performance. For a time there was much interest in this round, especially from special forces, but to date the only military users are guards regiments of Jordan and Saudi Arabia. Shortly afterwards, another challenger emerged in the form of the 6.5 mm Grendel (6.5 x 38). This uses a slightly fatter case (the same 11.3 mm diameter as the 7.62 x 39 Russian) which enables it to be shorter, thereby leaving space for longer and more aerodynamic bullets. This enables it to fire a 123 grain bullet at 2,350 fps from a 16 inch (406 mm) barrel (8.0 g at 716 m/s = 2,050 J), which has an excellent ballistic coefficient, retaining its energy very well out to long range.

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The photo shows the 5.56 x 45 M855A1, 6.5 x 38 Grendel, 6.8 x 43 Remington SPC and 7.62 x 51 M80, with their bullets. Note the bullets beside the 5.56mm: the new M855A1 (with an exposed steel tip) has the lead core element replaced by copper,

resulting in a significant increase in length to achieve the same weight as the SS109 next to it. The other bullets are all lead-cored; note the much more aerodynamic

shape of the 6.5 mm compared with the others (especially the rather stubby 6.8 mm) Another variation on this theme in the early 2010s was the 6.5 x 40, based on the 6.8 mm Rem case but like the Grendel using heavy bullets at modest MVs to provide a good long-range performance. Almost identical rounds were developed first by Mitch Shoffner and subsequently by the US Army Marksmanship Unit (USAMU). The designs of all of these rounds have been compromised by the need to keep within the 57 mm overall length of the 5.56 x 45, so that existing 5.56 mm weapons can be rebarrelled to chamber them. A clean-sheet design would probably result in an overall length of around 65 mm. A recent variation from Mitch Shoffner (now supported by Osprey Combat LLC) is the 6.5 mm SuperZ, which is similar to the 6.5 x 40 but has the case length extended to 43 mm. This makes the round too long to use in standard 5.56 mm actions, so a purpose-designed gun has been developed. An even more powerful round was developed around 2010 by Cris Murray, who had prviously been involved in the 6.8 mm Remington development. This was the 7 x 46

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UIAC (Universal Intermediate Assault Cartridge), which was based on the same 11.3 mm case diameter as the 6.5 mm Grendel. In its proposed standard loading it fired a 130 grain bullet at 2,650 fps (8.4 g at 810 m/s), developing 2,750 J; rather too powerful for the assault rifle role. These were mostly private US attempts to develop an improved infantry rifle cartridge which would provide a better performance than the 5.56 x 45 with less weight and recoil than the 7.62 x 51. They have in the past few years been overshadowed by two army programmes running in parallel: the conventional 264 USA and 277 USA from USAMU, and the LSAT / CT programme, of which more later. The 264 and 277 USA (which are identical in all respects except for calibre, being 6.5 x 47 and 6.8 x 47 respectively) also use a c.11.5 mm diameter case, so are similar in dimensions to the 7 x 46 UIAC and not far from the .270 British (6.8 x 46). They are of particular interest because part-polymer cases have been developed for them, saving around 21-22% of the overall round weights. They develop 2,600-2,700 J depending on the loading, so are likely to have controllability issues if used in assault rifles. On the other hand, they have the performance to replace the 7.62 x 51.

5.56 x 45, 6.8 mm Rem SPC (6.8 x 43), 6.5 mm Grendel (6.5 x 38), 264 USA (6.5 x

47), 277 USA (6.8 x 47), .260 Remington (6.5 x 51), 7.62 x 51 This is even more true of the .260 Remington, a commercial hunting and target cartridge which is essentially the 7.62 x 51 necked down to 6.5 mm; so modifying

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7.62 mm guns to fire it will involve little more than swapping the barrel. This round has attracted the attention of US special forces as a potential 7.62 mm replacement, as when loaded with heavy, low-drag bullets, it offers far better long-range ballistics. With an ME of over 3,000 J the recoil would make it a considerable handful in an assault rifle.

264 USA with polymer/steel hybrid case by MAC LLC All of this suggests that the original FCAR concept of assault rifle ammunition is being ignored, but it has recently made a surprising recovery, albeit in a niche role. The .300 Whisper cartridge uses a case the same diameter as the 5.56 x 45, but shortened to 35 mm and necked-out to 7.62 mm calibre. It was mainly intended to be loaded with heavy bullets fired at subsonic velocity, to be fired from carbines fitted with suppressors, for special operations requiring stealth. It has been around as a proprietary cartridge for many years but a few years ago what is effectively a copy (the two rounds are often although not always interchangeable) emerged as the .300 AAC Blackout, made by Remington. This has suddenly become very popular, which shows the benefits of a marketing campaign by a big company. It is available with both subsonic and supersonic loadings, the latter virtually duplicating the performance of the 7.62 x 39 AKM round in a smaller package. The attraction is that only a barrel change is needed to convert any 5.56 mm AR-15 rifle to take it, but this can also be something of a disadvantage since it is possible to chamber and fire some .300 ammunition in a 5.56 mm gun, with undesirable consequences. Carbines in this calibre are finding a niche appeal among certain special forces. Exotica 4 the Lightweight Small Arms Technologies Programme (LSAT) During the early 2000s the US Army funded the Lightweight Small Arms Technologies (LSAT1) development programme, with the aim of halving the weight of the current 5.56 mm M249 (FN Minimi) LMG and its ammunition. The AAI Corporation (now Textron) was the lead contractor for the project and responsible for the gun design. Two different cartridge designs were tested, shown below. One was a polymer-cased telescoped round (by ARES) now in "Spiral 3" - the third generation, the other a caseless round (by ATK) based on HK G11 technology. The caseless rounds saved 38% in volume, and weigh 6.3 g each compared with c.12.2 g for the M855 to give overall weight savings of 51% (due partly to the lighter plastic belt links). The plastic-cased Spiral 3 rounds were 40 mm long by 11.4 mm in diameter, saved 13% in volume, and weighed 8.3 g. They saved 41% in weight in MG belts compared with M855 belts, since the plastic links weighed 0.5 g compared with 2.0 g for the steel links. Total weight of a 200-round belt of Spiral 3 ammunition 1 http://www.dtic.mil/ndia/2016armament/18325_Phillips.pdf

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was 1.76 kg compared with 2.84 kg for M855.

Above: the LSAT 5.56 mm family: caseless above left, plastic-cased-telescoped

Spiral 1 (top right), Spiral 2 (centre) and Spiral 3 The emphasis was on developing LMGs (eight were built and extensively tested), but there was a programme to develop a carbine to use the same ammunition. However, by the early 2010s the 5.56 mm programme had been closed down as Army interest changed to a more powerful version in a larger calibre.

Textron 6.5 mm CT with 123 grain / 8.0 g EPR bullet (Nicholas Drummond) The first fruits of a new programme, now renamed Cased Telescoped Systems (CTS), matched the 7.62 x 51 in calibre and ballistics, but Textron subsequently focused on a 6.5 mm version of the round, using the same exterior dimensions as the 7.62 mm. Dimensions include a round length of 52 mm and a diameter of 12.7 mm, while the weight saving over the 7.62 x 51 is 35% (weight with an 8.0 g bullet is 15.3

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g). The claimed performance of this prototype is in the same league as the .260 Remington with an ME of 3,300 J; the carbine intended to fire the 6.5 mm will clearly be similar to an equivalent 7.62 x 51 carbine in its recoil characteristics and controllability. Whether that will be retained or reduced in power during further development remains to be seen.

CT 5.56 mm and 7.62 mm, next to the 5.56 x 45 and 7.62 x 51. The 6.5 mm CT has the same external dimensions as the 7.62 mm version (image courtesy of Textron)

The current arsenal Despite all of these experiments, small arms currently in service are relatively conventional, at least as far as the assault rifle element is concerned. With the break-up of the Warsaw Pact, several East European nations have switched to 5.56 mm NATO weapons, either bought-in or of their own design. Even Russia is now offering Kalashnikovs for export sale in 5.56 x 45 as well as its domestic calibres. The US Army has switched to the M4, a carbine version of the M16 with a shorter barrel. In 2012 US planned two parallel programmes: a product-improved M4 in competition with a separate contest for a new Individual Carbine. The contest was cancelled in 2013, leaving the improved M4A1 (with a heavier barrel and a full-auto rather than burst-fire switch) as the Army assault rifle for the foreseeable future. The US Special Operations Command (SOCOM) selected the FN SCAR rifle/carbine

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in Light (MK16 in 5.56 x 45) and Heavy (MK17 in 7.62 x 51) versions, although they are currently focusing just on the MK17. Heckler & Koch has achieved sales success with the G36 and now also offers paired 5.56 mm and 7.62 mm weapons, the HK416 (adopted by Norway and France, plus the USMC as the M27 Infantry Automatic Rifle) and HK417 respectively, as does Colt with its CM901 which can be converted from one calibre to the other. Several other countries have also been developing new 5.56 mm rifles, notably Beretta in Italy with the ARX-160, plus Poland with the modular MSBS (interestingly, planned to be available in traditional and bullpup forms) and the Czech Republic with the CZ805 Bren (reviving a famous name), plus others in Asia and the Americas. All these weapons (except the MSBS) use a traditional instead of bullpup layout, in contrast to the Chinese QBZ-95, the Israeli Tavor, STK's SAR-21 and their new BMCR (Bullpup Multirole Combat Rifle) from Singapore, the Belgian FN2000 and the first 5.56 mm bullpup to enter service, the Austrian Steyr AUG, which is still offered (and recently adopted by Australia) in updated form. All of these weapons except for the 5.8 mm QBZ-95 are chambered for the usual 5.56 x 45 NATO. The traditional layout is preferred by many as it is easier to switch sides and use left-handed, but it carries the penalty of a much shorter barrel for the same overall length. The problem with short barrels is that they reduce the muzzle velocity, and the 5.56 mm bullets rely on a high impact velocity to yaw on impact and fragment (something which is not guaranteed with the SS109/M855 ammunition, even from rifle barrels). At lower velocities the bullets are even less likely to fragment and much of the wounding potential is lost. The US Army's current preference for the short-barrelled M4 has restarted this argument, with the terminal effectiveness of the 5.56 x 45 becoming controversial once again. The pros and cons of the bullpup vs traditional layout are explored in another article1.

5.56 x 45, .300 AAC Blackout, and Russian 9 x 39 AP

1 http://quarryhs.co.uk/bullpups.htm

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Some interesting special purpose assault rifles have come from Russia. They have fielded in various assault and sniper rifles, notably the AS "Val", a unique 9 x 39 round firing a very heavy bullet at subsonic velocity (16 g at around 300 m/s), with the much the same purpose as the .300 Whisper / Blackout, but without a supersonic load option. They have also developed an unusual carbine and ammunition combination suitable for firing below as well as above water: the ADS rifle and its 5.45 x 39 PSP round. Unlike earlier underwater guns, this does not fire a very long rod-type projectile, but instead a supercavitating one which is small enough to fit into the standard dimensions for the usual AK-74 cartridge. The ADS can therefore be switched between underwater and above-water ammunition simply by changing magazines. The Future? Is the assault rifle still a viable concept? This type of individual weapon still dominates the world's armies, mostly in 7.62 x 39 and 5.56 x 45 calibres, together with the Chinese-only 5.8 x 42. There are no indications that this will change in the near future. However, there are signs of a resurgence of interest in the 7.62 x 51 calibre at section / squad level, because of the limited range and hitting power of the assault rifle ammunition. This particularly applies to marksman / sharpshooter rifles and to belt-fed MGs, plus special forces, but Turkey and India both recently decided to revert to the larger calibre for their new standard infantry rifle. One terminological issue arises over what to call these new 7.62 x 51 rifles. The earlier generation of 7.62 mm mostly semi-automatic rifles with full-length (>20 inch) barrels are often informally referred to as "battle rifles" to distinguish them from assault rifles. However, the new versions tend to have shorter barrels and selective fire (however debatable the value of that might be with FP ammunition), and in some cases are almost identical to their 5.56 mm equivalents, so it makes little sense to give them a different name. Perhaps it's appropriate to introduce sub-categories, and call them "light" and "heavy" assault rifles, as with the SCAR. In the long run, these terms may disappear anyway. There is a long-held desire among some in the military to have all of the squad's firearms using the same ammunition a general purpose cartridge. This was the aim when the 7.62 x 51 was introduced, but that round recoils too much and is too heavy. Many armies tried again with the 5.56 x 45 when that was introduced, but that has insufficient effective range and is too light. There is now growing interest in something intermediate in size, with a long-range performance matching the 7.62 x 51 but with significantly less weight and recoil. This is discussed in detail in another article1, so the arguments for and against will not be addressed here. Whether such a GPC is ever adopted remains uncertain, but if it is then armies can revert to an old term for their individual weapon: "The Rifle".

1 http://quarryhs.co.uk/TNG2.pdf

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.276 Enfield (7 x 60); 6.5 mm Arisaka Type 38 (6.5 x 50SR); .276 Pedersen (7 x 51); .270 British (6.8 x 46); .280/30 British (7 x 43); 6.25 mm British prototype (6.25 x 43); 6.25 mm British proposed (6.25 x46); 6 mm SAW (6 x 45); 7.62 mm NATO (7.62 x

51); 5.56 mm NATO (5.56 x 45); 6.8 mm Remington SPC (6.8 x 43); 6.5 mm Grendel (6.5 x 38); 7 mm UIAC (7 x 46); 7.62 mm M1891 Mosin Nagant (7.62 x 54R); 7.62 mm M1943 AK (7.62 x39); 5.45 mm AK74 (5.45 x 39); 5.8 mm Chinese (5.8 x 42).

Service Cartridges Metric Size mm Bullet Weight g Velocity m/s Energy joules 6.5 Arisaka (Type 38) 6.5 x 50SR 9.0 (pointed) 762 2,600 6.5 Carcano 6.5 x 52 10.5 700 2,570 7.35 Carcano 7.35 x 51 8.4 756 2,400 7.9 Kurz 7.9 x 33 8.1 686 1,900 .30 Carbine 7.62 x 33 7.0 580 1,200 7.62 M1943 AK 7.62 x 39 7.9 710 2,000 7.62 vz52 7.62 x 45 8.4 744 2,320 7mm Medium 7 x 49 9.0 840 3,175 5.45 AK 74 5.45 x 39 3.5 900 1,420 5.56 NATO 5.56 x 45 3.95 930 1,700 5.8 Chinese (DPB 10) 5.8 x 42 4.6 915 1,925 7.62 NATO 7.62 x 51 9.33 838 3,275 7.62 M1891 Mosin Nagant 7.62 x 54R 9.75 835 3,400 A follow-up article looking at the characteristics of the next generation of military small arms is here: http://quarryhs.co.uk/future%20small%20arms.htm Readers wishing to learn more about this subject will be interested in 'Assault Rifle: the Development of the Modern Military Rifle and its Ammunition' by Maxim Popenker and Anthony G Williams. Details are here: http://www.crowood.com/details.asp?isbn=9781861267009&t=Assault-Rifle Sources: Hogg, I and Weeks, J. Military Small Arms of the 20th century Dugelby, T.B. Modern Military Bullpup Rifles Long, D. Combat Rifles of the 21st Century Stevens r. and Ezell, E. The SPIW: The Deadliest Weapon That Never Was Huon, J. Military Rifle and Machine Gun Cartridges Hogg, I. Jane's Directory of Military Small Arms Ammunition Labbett, P. Assault Rifle Ammunition 5.6mm to 11mm Calibre

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___________________________________________________________________ The home website is at: http://quarryhs.co.uk/index.html Links "The Next Generation: the case for a new NATO rifle and machine gun cartridge" http://www.dtic.mil/ndia/2010armament/WednesdayLandmarkBAnthonyWilliams.pdf "The M14 Enhanced Battle Rifle" in the American Rifleman, February 2011 http://www.americanrifleman.org/articles/2011/2/23/the-m14-enhanced-battle-rifle/ "Towards a 600 m lightweight General Purpose Cartridge, v2015" by Emeric Daniau, DGA Techniques Terrestres http://quarryhs.co.uk/600mv2015num.pdf "Time for a Change: U.S. Military Small Arms Ammunition Failures and Solutions" http://www.dtic.mil/ndia/2008Intl/Roberts.pdf "Increasing Small Arms Lethality in Afghanistan: Taking Back the Infantry Half-Kilometer" http://www.dtic.mil/get-tr-doc/pdf?AD=ADA512331 "Army, Marines face new pressure to use same ammunition", Army Times 4th May 2015 http://www.armytimes.com/story/military/tech/2015/05/04/army-marines-face-new-pressure-to-use-same-ammunition/26657177/ "Dual Path Strategy Series: Part III Soldier Battlefield Effectiveness" http://usarmy.vo.llnwd.net/e2/c/downloads/215919.pdf ______________________________________________