Wednesday 19 May 2021

D-25 vs D-10

F.16 Op.2154 D.4"Top Secret
To the People's Commissar of Armament of the USSR, comrade D.F. Ustinov

On your orders, we report on the issue of replacing the D-25 gun in the IS tank with the D-10T.

  • Due to the higher rate of fire of the D-10 compared to the D-25, chiefly due to the single piece ammunition, it is reasonable to make this change, but only if an armour piercing shell is developed equivalent in penetration to the D-25's shell.
  • No such shell is being produced at this time.
  • We consider it necessary to preserve the D-25 gun in the IS-2 heavy tank. The latest trials at the ANIOP show a rate of fire of 4-6 RPM, this is a good result.
  • The factory is wrapping up preparations for D-10S production in August-September of 1944.
  • All armament production can be moved to produce the D-10T instead of the D-25 in October-November.
  • 150 D-10T guns can be produced in October, 250 in November.
  • To achieve this, factory #9 requires 4 600x6000 roughing lathes and two #6 milling machines.
  • Production of D-25S guns should then be transferred to factory #75 or #221 in October.
August 8th, 1944"


  1. Isn't it odd that they always bring up that the D-10 has no AP shell as good as the D-25?

    It seems like they always refer to the penetration test against the Panther, where the D25 could penetrate the upper plate at 2.5km and more.

    I mean it's a heavier shell so it will probably out perform the D10 at some point... :D

    Even the Tigers 8.8cm KwK 36 outperforms the Panthers 7.5cm KwK 42 at around 1.6km

    1. I'd agree with the longer range thing with APHE, though also it's an advantage when the gun's HE round is potent enough to effectively take out any vehicle. The D-25's HE round could do that; the D-10, not so much. Given the relative ammo types carried by the IS-2 (I've read typically 3 OF-471 shells per each APHE) they probably went into action with the OF-471 in the breach by default.