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ng. 1■r*or plnte ball oaitlng 'tf'<r'ln,3 effoot of nomal Imppct of cal, aarvlo* velocity, a,p, tmllots at 100 yds,rang*. XI

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(«atartcAn Ar««nal Htport No. 710/» StpU.btr 2i. Ifr33.

«•port of aalllgtlc Ttst on Ar»or Plate Ball CaatinÄS, Dwg. No. C63£5e for Tank

T?S£ - P.c. 6107

3p«cl«an aaiaeiad was axaaadlnflj porout. following

haat treatment «as given before flrat teat:

Normalizing:

6 hours at 1150°c - air cool " n 4 " • 950"C - -

4 ■ " 8500C - furnace cool

Hough Machined:

1 1/t hour« at 1600Jf - oil quench 11/8- " 1000^ - furnace cocl

Flrinfi «as then done at 100 yda. «1th serrice Telocity

.30 cal. a.p. asiaunitlon «hich has a rated residual voloclt

of 2480 ft/eec at that range. Hits of normal impact were

registered in both sound and porous structure on the flat

surfacs and in porous structure on the spherical surface.

In all caaesof hits In porou« astal the bullets changed

directlcn eharply and tore theneelves cut normal to their

line of flight penetrating not acre than 1/2". The impact

on sound metal gave nc evidence of the bullet having change-

direction and the penetration »as apparently about 1/8".

No ■easurement «as made of penetration at this time as all

hits were on sections of the casting of at least 3/4- thick

nees.

■^rinell hardness of specimen;

Flat Surface 424 Spherical ■ 3&5

REPRODUCED AT GOVERNMENT EXPENSE

Thi specimen as then annealed: 4 hours at 8500C and

furnoe cooled, «achln^d to a thickness of between 1/2"

and 5/3" and hardened os follow«:

1 1/S hours at 1600jr - oil quench 11/2" " ICOCTF - furn.ics cool

Firing «as conducted at 100 yds. range eal. .ZC,

service velocity a.p. aamunltlon and normal licpact obtainad

on both flat and«pherloal surfacee.

Tabulated results:

~7~ arin*11 «.. Depth cf Nature of Nature of •JUrf•0• Thickness Penetra- Metal Metal on tiw Struck Cppotite aids Flat 418 19/32" 32/64" 3cund Porous Spherical 444 17/38" 31/64" " r^ou»

In each case the Impact of the bullet «as directly

opposlts an intsrior surface In which were bio* holes of a

diameter and depth of at least 1/8". The inner surface showed

only a rsry slight protrusion and In nelthsr case any sign of

cracking, spalrling or complete penetration as defined in U.n.

ArmyLTentatlve Specification for light armor plate, AX? F,ev. 1,

Kay 1, 1933. Photographs of hits Figf. 1, 8 and 3.

Rtqulrsmenla for BalliPtlc rssl tance for hcirogensoas

armor plate:

250C f/sec for .ZC cal a.p. oullato on

.500" thickness, no oomplsts pönetra-

tion (U.S. Army lentatlve Specification

for light Armor Plate, AX3 Pev. 1,

Miy 1, 1^23).

D. b. crawlffiv A 1st lt., Crd. Dept.