SHERMAN TANK MYTHS - HYPER-SHOT (HVAP OR APDS) WAS NOT FEASIBLE FOR THE 75-MM ON THE SHERMANCopyright 2015 JDNealPreviously posted as: WHY NOT FIELD HYPER-SHOT (HVAP OR APDS) FOR THE 75-MM ON THE SHERMAN? but promoted to a myth for the reasons explained below.The first time I read this I fell for the trap everyone else does, so I will retain that as a lesson to myself and everyone else concerned:The 57-mm M-1 anti-tank gun (British 6-pounder) and 76-mm M-1 gun were given a serious boost in anti-armor value with the development of APDS (armor piercing discarding sabot) shot for the 6-pounder by the British and HVAP (High Velocity Armor Piercing) ammo for the 76-mm by the USA. Which begs the question: why not develop HVAP ammo for the 75-mm M-3 gun mounted on thousands of Shermans (and carried in kind on hundreds if not thousands of British tanks as their home grown 75-mm Quick Firing gun)?First off, the USA made a mess of its own HVAP ammo, which illustrates how uncoordinated and idiotic gun design was in the USA. It did not develop similar ammunition for the 57-mm and hence US anti-tank gunners equipped with 57-mms had to use British ammunition - if they could acquire it.When it came to 76-mm HVAP ammo, there was a low priority (as with all things in the US military in World War II) because the decision makers had been erroneously told the 76-mm and 75-mm were just fine. Once they proved mediocre against the frontal armor of better protected German vehicles, issue of HVAP ammo almost had to be shoved into the field by the general staff. Even then it had to be rationed, as ammunition shipments were in the tens of thousands per month and there were thousands of tanks and anti-tank guns to use it. The 3-inch version took priority for M-10 gun motor carriages and towed 3-inch anti-tank guns of the tank destroyer units; M-18 Hellcats had priority for 76-mm ammo; and tankers got what was left over of 76-mm ammo.If only the USA had dumped the 3-inch gun for the M-10 and anti-tank gun and used the 76-mm, things would have been better for tankers because around 60% of the shipments were 3-inch ammunition. Even though 3-inch guns were among the least common weapons in use. This descrepncy occurred because there was favoritism for the tank destroyer units from the top.Anyway: the design that the USA used for HVAP ammunition increased penetration by 50% over standard ammunition: thus a common 76-mm AP shot would penetrate about 4-inches (100-mm) of armor, and the HVAP 6-inches (150-mm) or so.Using that as a pattern, any HVAP ammo they might have designed for the 75-mm M-3 would likely have penetrated 4.5-inches (around 115-mm) of armor - given that standard 75-mm M-3 AP shot could penetrate about 3-inches of armor. This would give some chance of taking a Tiger on from the front and perhaps a Panther with accurate shots at close range. Having a plentiful supply of 75-mm HVAP ammo certainly might have helped, but the USA was hard pressed to supply enough to the 3-inch and 76-mm guns to be of use. And they had 2 to 3 times as many 75's as 3-inch/76-mm guns.So, in the end, fancies of the imagination usually get stomped on by the realities of the situation!Actually, the USA did devlop a HVAP 75-mm shot and it performed as I previously speculated. As someone else ponted out, though, each round of 75mm HVAP ammunition would have been 1 less round of 76-mm/3-inch HVAP.Indeed, a properly designed 75-mm HEAT (hollow charge) round would have penetrated 6-inches (150-mm) or more of armor, and while not as reliable and accurate at long range as the 76-mm, it would have given all those 75-mm armed tanks (and 75-mm howitzers) a big boost in short range armor fighting. Without need of anything fancy.But USA HEAT shells in use back then were also mediocre...OOPS! I FELL FOR THE SAME TRICK EVERYONE ELSE DOES. The number one reason given for the use of tungsten in these hyper-velocity rounds is that common, hard, heat-treated steel rounds tend to shatter when striking thick armor once they reach certain velocities: the cap on armor-piercing capped (APC) ammunition helps counter this and seems to extends it to velocities used by German long 75s and 88mm KwK 43s - 3000 to 3,2000 fps.That, though, distracts from an important point. According to the scant information I have found about the 75-mm T45 HVAP round, it used a 3.3 kilogram/7.25 lb shot at 870 mps/2,870 fps and penetrated 117mm of armor at 30 at 500 yards. The French were among the first developers of the APDS concept and perhaps they brought it to the British attention: in 1940 they had worked out a round firing a 57-mm shot at 900 mps/2,920 fps that could penetrate 90-mm 1000m at 35. (No weight is given.) They intended to use this to improve their own 1897 era 75s.NOTICE THOSE VELOCITIES! They are well under the velocity that steel shatters at. Indeed, they are the same velocities of 57-mm and British 17-pounder APC functioned at. Indeed, using my own formulas and various tables, the penetration quoted seem to be for simple 57-mm shot at given velocities. The USA 3.3 kilogram/7.25 eight of the T45 corresponds directly to the USA's AP-HE version of the M86 ammunition (with a velocity of 2,700 fps). And French 57-mm shot performance works out for a 6.25 pound shot.The French had developed this sort of ammunition back in 1940. It did not require tungsten; it was an easy fix; it could have been produced in quantity for the 75 in 1942 let alone 1944.The US Armys own General Staff and technical staff simply did not have the gumption to give US tankers a better weapon than they had. Even though doing so would have been pretty simple and easy!Indeed, the 40-mm Bofors round used a powder charge less than 1 pounds, which was the heavy load for the 75-mm howitzer. Adopting the 40-mm shot of the M81 AP round (or a heavier projectile) to the howitzer case this way would have likely given the howitzers a high velocity round with 2.5 (65mm) of penetration.I personally keep looking for answers an finally ran across the doument "a800118.pdf" (which might be found as "ADA800118") which describes "Work on Sabot Projectiles by University of New Mexico" from 1942 to 1944. It details the U.S. Army's development of HVAP ammunition and provides many details. Most notably, the US Army did indeed want to use a 57-mm common steel AP shot for the 75-mm M3 gun. Work was also done creating a sabot round for the 75-mm howitzer and the 105-mm howitzer using steel AP shot.The last two had doubtful application since HEAT ammunition then available performed better than what was created and there were other issues like "jumping". Still, the Artilerymen were considering replacing the 57-mm gun with the 105-mm M3 howitzer as their self-defence anti-tank weapon if a valid HVAP round was provided. Thus, they could use the HE and smoke rounds for howtizers for common use and have an AT defense.Someone will doubtlessly defend the Army and Ordnance by noting that cannon such as the 76-mm and 90-mm were in the works, so HVAP ammunition wasn't really needed for the 75mm. Somehow they miss the point that (a) said cannon were only put into the field after the duress of meeting a plentiful supply of Panthers, Tigers and well armored German tanks in mid-1944 on, (b) that 75-mm gun armed tanks were the mainstay of the British and US armies and (c) somehow they toss away the idea that common tankers didn't deserve better armor piercing ammunition than what they were given. If the 75-mm HVAP round using plain steel shot had been polished a bit more and issued in the tens of thousands, US ground forces would have been far more effective in their job!Supplying this shot would not have effected supplies of HVAP for the 76mm and 3-inch because it DID NOT USE TUNGSTEN!Giving tankers the tools they needed was not high on the Army's list of priorities, though.