17-Pounder APDS issues IRL

[John Kettler]

My recollection from CMBN is that BFC did not model erratic performance of 17-Pounder APDS. Is this correct? If so, I believe it gives the British a consistent level of APDS performance they simply didn't have. If, for example, the Firefly TC, following the almighty, tracer obscuring muzzle blast and huge dust cloud of outbound projectile finds APDS finds going wildly off target, then it seems to me worth factoring into the game as a "die roll" under the hood. Be these as they may, while looking up something for brother George, who's building a simplified set of armor rules for use with Bolt Action, I found this old thread with some great grog stuff on why theoretically easy tank penetrations weren't happening. For terminal ballistics enthusiasts, this is great stuff. Participants? Some guy named rexford, another named John D Salt, plus flaming knives and Mr. Tittles.

The Isigny trials show conclusively the accuracy problem with the 17-Pounder APDS projectile was huge, not minor. Just look at how that projectile stacked up against the APCBC fired from the same gun and in relation to other tank guns. Bold mine. 43% of the APDS shots missed vs none for the APCBC projectile!

http://www.armchairgeneral.com/forums/showthread.php?t=61681

b. Accuracy

(1) A tabulation does not present a true picture of the comparative accuracy of the various ammunitions. With all the standard rounds, except 17pdr SABOT, the accuracy was such as to warrant attempting to hit specific parts of the front plates. In general this was successful, but some rounds fired at the lower glacis struck the upper nose, and vice versa. In addition, it was not possible to position all the tanks so that the nose was not, at least partially, hidden by the ground line. Therefore, it is felt that a better measure of accuracy can be obtained by considering the nose and glacis as one target.

(2) On this basis all twenty-two (22) rounds of 76mm HVAP, T4, and all twenty-three (23) rounds of 17pdr APCBC hit the target. Only one (1) of eight (8) rounds of 76mm APC, M62, which fell short attempting to hit the nose, failed to hit the target. Forty-two (42) rounds of 17pdr SABOT were fired and only 57% [24 rounds] were hits. More rounds of 76mm APC, M62 were not fired since its accuracy had been well established in previous firing in the U.S. by two members of the board.

(3) Insufficient firing was conducted with 76mm HVAP projectile with 17pdr APCBC and 17pdr SABOT propellant to determine definite sight settings for a conclusive accuracy test. The results of the limited firing indicated that these rounds are of an accuracy comparable with 76mm HVAP and 17pdr APCBC.

 BBC's WW2 People had this on APDS. It should be of interest.

http://www.bbc.co.uk/history/ww2peopleswar/stories/06/a2187506.shtml

Regards,

John Kettler

[Warts 'n' all]

Can't help but think the key words from Aunty Beeb's piece is "over long ranges".

[JoMac]

It's to bad these Tests, and any BF Armor/Ballistics Modeling (much latter) weren't incorporated into 'Tractics' back in the day :-(                                                                            

I still remember in one example; the U.S. M4/76 Gun needed to use HVAP (APCR) to penetrate the Upper Hull of Panther (AP couldn't as Upper Hull was around 160mm or 80mm@55 degrees), since HVAP penetrated something around 200mm.

Now, newer Data (or rather older Data that was never incorporated into Rules) showed this to be improbable as even 76mm APCR couldn't penetrate Panther Upper Hull (or even U.S. 90mm Gun).

I wonder how many other WWII Miniature Rules from the 70's-90's are totally wrong about this (I know many are). 

Joe

Edited September 21, 2016 by JoMc67