Home › Forums › WWII › Kursk assault—another 6mm playtest of A Sergeant's war › Reply To: Kursk assault—another 6mm playtest of A Sergeant's war
I’m replying in this thread because the forum software won’t let me post in the other one… weird.
Gonna give you a shout-out in the rules if that’s cool with you
Fine by me — thanks very much.
The classification I suggested might be seen as generous to the Soviet 45/66, but in any classification scheme there are going to be cases near the borders between classes. The scheme I suggested preserves the distinctions between L45 and L66 versions of the Soviet 45mm, L45 and L52 versions of the British 6-pdr, and L42 and L60 versions of the German 5cm, but loses the distinctions between the L30 and L40 versions of the US 75mm, the L30 and L41 versions of the Soviet 76mm, and the early and late propellant loadings for the US 90mm M3. It also makes the 3.7cm PaK 36 as good a gun as the British 2-pdr or US 37mm, which it wasn’t.
Ivan Sorenson is right that “Sometimes smaller guns can be deceptively efficient tank-killers.” The 6-pounder and Soviet 57mm are especially notable; all the numbers I’ve come up with show that the 57mm is as good a gun as the 85mm in terms of armour penetration at close range. Small-calibre high-velocity projectiles concentrate more kinetic energy per unit area than bigger rounds, and it’s energy loading that gets you penetration.
The classes I suggested were based on an objective calculation using Dehn’s penetration formula on the calibre, mass and muzzle velocity of the projectiles known to me, with a nominal reduction of velocity for a range of about 250 metres. I then subtracted 12mm from the resultant penetration and divided by 25.4 to give the categories. One slight bit of fiddling; I bumped the long 88mm up by a millimetre to put it in the top band. This is of course an entirely arbitrary procedure, and is always possible to do slightly different sums that will result in guns at the margins going up or down a category. However, I think the categories given correspond really very well to my established prejudices about the relative performance of different weapons, while keeping to the spirit of the broad-brush approach you are taking. Incidentally, I think you are quite right to concentrate on things other than the fine details of armour penetration. Somewhere I have a British OR report from 1944 or so which says that first-round hit probability, rather than armour penetration performance, is the dominating factor in anti-tank engagements.
Still, it’s worth pointing out that penetration isn’t the whole story when it comes to tank-killing. Hit probability I’ve mentioned, and there’s also the question of behind-armour effect. Other factors being equal, lower-velocity guns have an advantage in consistency (less muzzle pressure means less angular dispersion at the muzzle) and heavier projectiles have an advantage in carrying power (retaining their velocity, and hence penetrating power, down range), so that, for example, the 75mm M3 would still shoot with reasonable accuracy out to 2000 metres, whereas the 6-pounder would be putting rounds all over the place at that range. Such long-range advantages obviously will not show up in your game of the “knife fight” at 500m or less, so one should expect to see the bigger and lower-velocity guns at more of a disadvantage than they would be at longer ranges.
As to behind-armour effect, there is very little information I can find on the subject, but it should be obvious that 15 pounds of metal entering your tank at high speed is worse news than six pounds, and this is where the bigger guns have an advantage. If you wanted to show this, you might have a slightly different damage table for “small” rounds — let’s say. those below 65mm in calibre — like this:
1 or less = Destroyed
2 = Damaged
3, 4, 5 = Morale
6 or more = No effect
Since their penetrators are all smaller than 65mm in calibre, I’d suggest also using this table for all special ammunition, HVAP, APCR, APDS, APCNR and HEAT. Using this rule, the “standard” US 75mm and Soviet 76mm guns would be slightly better than the PaK 38 or 45mm Model 42, despite having the same penetration value, and it makes the T-34/85 preferable to the T-34/57.
All the best,
- This reply was modified 6 years, 7 months ago by John D Salt.