rexford Posted February 11, 2004 Share Posted February 11, 2004 John Salt has done a bang up job of finding and posting a horde of British, and American and other nation penetration stats for WW II. The following data from Salt's compendium provides some silly Allied data that may have gone into the decision to emphasize 75mm Shermans instead of 76mm Shermans: WO 219/2806, Appendix G to SHAEF/16652/GCT/Arty July 11, 1944, penetration data at 30 degrees strike: US & Br 75mm M61 APCBC ======================= 100mm at 600 yards, 93mm at 1000 yards, 82mm at 1600 yards US 76mm APCBC M62A =================== 97mm at 600 yards, 90mm at 1000 yards, 80mm at 1600 yards Salt notes that a memo in the document states that there seems "little to choose" between the 75mm and 76mm. Given that the 75mm and 76mm APCBC rounds were fired at 619 and 792 m/s respectively, and the 76mm ammo outweighed the 75mm by 15.44 to 14.96 pounds, one would think that someone would have figured out that 75mm APCBC could not outpenetrate 76mm APCBC at all ranges before the info found it's way into an official document. Assuming the above data is correct means that the Sherman 75mm could penetrate the Tiger driver plate at 500m with a 30 degree side angle! And the Tiger 82mm side plates would be vulnerable to 75mm APCBC at 1600 yards and a 30 degree side angle! I checked the American stats for aircraft use of the Sherman 75mm gun, which added 350 mph to the muzzle velocity, and the 75mm M61 would still not outpenetrate 76mm M62. 0 Quote Link to comment Share on other sites More sharing options...
JasonC Posted February 11, 2004 Share Posted February 11, 2004 It is probably flat data for the 75 and 30 degree data for the 76... 0 Quote Link to comment Share on other sites More sharing options...
rexford Posted February 11, 2004 Author Share Posted February 11, 2004 Originally posted by JasonC: It is probably flat data for the 75 and 30 degree data for the 76... That possibility is not possible given the data in the report. The 75mm M61 penetration against vertical armor is 81mm at 500m, the SHAEF report appendix has 100mm at 600 yards (549m) for M61 APCBC. Someone did something really unbelievable and no one caught it prior to publication. 0 Quote Link to comment Share on other sites More sharing options...
rexford Posted February 11, 2004 Author Share Posted February 11, 2004 John Salt's data provides an interesting comparison of Sherman 75mm AP and APCBC that reverses the traditional penetration relationships. Because 75mm M72 solid shot AP did not have an HE burster and had a pointed nose, it outpenetrates 75mm M61 APCBC against homogeneous armor (100m and 500m) in all the data I've ever seen. However, British report WO 185/178, dated 1943, shows 75mm M72 AP penetrating 88mm of homogeneous armor at 500 yards and 75mm at 1000 yards, while 75mm APCBC defeats 94mm at 500 and 85mm at 1000 yards. U.S. data for 75mm M72 AP has 92mm at 500m and 76mm at 1000m, which is slightly higher than the British report but fairly close. Where are the Allies getting 94mm/0 degrees for Sherman 75mm APCBC at 500 yards in one case, and 100mm/30 degrees at 600 yards in another? TM9-1907 has 81mm/0 degrees at 500m for 75mm M61. Looking like alot of bogus and overinflated penetration stats floating around for Sherman 75mm in days leading up to and slightly after D-Day. 0 Quote Link to comment Share on other sites More sharing options...
John D Salt Posted February 29, 2004 Share Posted February 29, 2004 Originally posted by rexford: John Salt's data provides an interesting comparison of Sherman 75mm AP and APCBC that reverses the traditional penetration relationships.Ah, but it's not my data, I merely report it... [snips] Originally posted by rexford: Looking like alot of bogus and overinflated penetration stats floating around for Sherman 75mm in days leading up to and slightly after D-Day. Indeed so. WO 219/2806 (a copy of a SHAEF, rather than a "British" document, btw) also quotes some deeply silly statements from an ordnance officer (mercifully unnamed) in the USA who claims that the 76mm will penetrate the Panther's glacis up to 1,600 yards, which implies to me that the officer in question is unaware that the Panther's glacis is sloped. The 75mm penetration data Rexford has highlighted seems to me to be the most wildly inaccurate piece of numerical penetration data I have yet collected. Possibly the belief (reported in Bill Close's book "Panzer Bait") of British technical intelligence that the 88mm Flak 36 and 75mm L/24 had similar penetration performance is sillier, but at least those were enemy, rather than friendly, guns. For some reason, similarly over-optimistic figures for the 75mm are given in the 1975 Bovington Museum booklet "Fire and Movement". This refers to the British 75mm Mk V, which should be ballistically practically indistinguishable from the US 75mm M3. The idea that figures for normal penetration have mistakenly been quoted as being for 30 degrees is not impossible -- I have found Ian Hogg make the same error before now -- but in this case the Bovington booklet states the m.v. of 75mm APCBC as being 2,650 ft/sec. That is faster than the m.v.s given for the 6-pdr, 77mm or US 76mm APCBC rounds, and would certainly produce pretty good performance if true. The trouble is, I have never heard of any ammunition being issued for the 75mm with such a high m.v., and I think it would take more than just a pinch of bicarb to improve the performance of the cartridge by that much. All the best, John. 0 Quote Link to comment Share on other sites More sharing options...
JonS Posted March 2, 2004 Share Posted March 2, 2004 Wot ho Squiffy? He's back! 0 Quote Link to comment Share on other sites More sharing options...
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