Yak-9T - incredible firepower (or maybe incredible tank's lack of armor?)

[gaunt1]

I dunno. That 140mm sounds unbelievable to me. If you check the link about modern ammunition, you can see that such performance was only possible with APFSDS munition (Bofors). Also, the much larger ZIS-2 AT gun was capable of penetrating 145mm armor @ 500m, with tungsten ammo.

I read somewhere that the reason why the Gemans desperately tried to mount the PaK40 on aircraft was because the BK 3.7 was totally useless against IS-2 and ISU-152 tanks, both with 30mm top armor.

From russianammo.org:

Ammunition used in the NS-37:

BT, AP-T, bullet weight 760g, muzzle vel.: 880m/s, Penetrated 50mm of armor at 200m.