
Some more British tests. A bit of transition to the British version of the M3 75mm gun which is the Q.F. 75mm Mk V. This fired the M72 round as well as the M61 with an inert filler. 8. WO 291/238 AORG Report No.256 "The Importance of Gun Dispersion in A.P. Shooting" provides data comparing accuracy/dispersion of tank mounted guns. This gives the following data for a number of tank guns at 1000 yards range. (presumed to be 90% zone) To find the German 50% zone from UK 90% zone divide by 1.22, Gun dispersion 75mm M3 APCBC (M61) 2.2 mins Tangent (2.2/60) x 1000/1.22 = 0.443 yd. *[0.44 yd] 75mm Mk.V APCBC 3.0 mins Tangent (3/60) x 1000/1.22 = 0.715 yd. *[0.60 yd] 76mm APCBC 1.4 mins Tangent (1.4/60) x 1000/1.22 = 0.334 yd *[0.28 yd] * Alternately using the BA program to find dispersion that results in 90% hit chance of dispersion sized target.
76mm M1A1 and 90mm M3
9. Weapon Research Committee: accuracy of antitank guns and rigidity of gun barrels", 1948 [PRO piece number WO 195/10134], Gun Ammunition m.v. (f.p.s.) Ave m.d. of strike 76mm M1A1 APCBC 2600 0.5' : tangent (0.5/60) x 1000 x 1.69 = 0.246 yd. AP/T 3400 0.5' : tangent (0.5/60) x 1000 x 1.69 = 0.246 yd. 90mm M3 APC 2600 0.3' : tangent (0.3/60) x 1000 x 1.69 = 0.147 yd. AP/T 3350 0.5' : tangent (0.5/60) x 1000 x 1.69 = 0.246 yd.
10. Armor Piercing Ammunition for Gun, 90mm, M3 M82: APCBC 2800 f/s extreme horizontal dispersion 41 in., vertical 70 in. at 2100yds. T33: AP 2800 f/s extreme horizontal dispersion 16 in., vertical 19 in. at 700yds. T30E15: HVAP 3400 f/s extreme horizontal dispersion 17 in., vertical 30 in at 2100 yds. M82: 41/36 x 1000/2100 = 0.542 yd, 70/36 x 1000/2100= 0.956 yd; T33: 16/36 x 1000/700 =0.635 yd, 19/36 x 1000/700 = 0.754 yd. T30E15: 17/36 x 1000/2100 =0.225 yd, 30/36 x 1000/2100 =.0397 yd. The question now becomes what do they mean by extreme? Is that the 90%, 95% or 99.7% zone? So we might as well figure out the numbers in all cases. 90% zone = 2.44 x 50% zone, 95% zone =2.91 x, and 99.73% is 3 x. Since this is a US zone I assume it must be divided by 2 to conform to German/Russian standards. [90%,95%,99.7%] Giving: M82: h=[0.444, 0.373, 0.381] v=[0.784, 0.657 , 0.637] T33: h=[0.52, 0.436 , 0.423] v=[0.616, 0.518 , 0.503] T30E15: h=[0.184, 0.155, 0.15] v=[0.325, 0.273, 0.265]
The results are somewhat confounding. The US/UK 75mm guns sometimes have small dispersion, sometimes large. It might be attributed to differing quality lots of ammo or maybe something else for the unusually small dispersions. One reason may be the way probable statistics are defined. At least in regard to US/UK definitions of percent zones as compared to German/Russian definitions.

