"October 13th, 1943
To the Deputy Chair of the GAU ArtKom, Major-General of the Engineering Artillery service comrade Zhevanik
CC: Chief of the Gorohovets ANIOP, Engineer-Lieutenant-Colonel comrade Grandilevskiy
RE: sending materials on the D-25 122 mm gun
I send you letter #1468/35s from factory #9 written on October 9th, 1943, with materials on the D-25 tank gun.
The D-25 tank gun was designed and produced by NKV factory #9 according to GOKO decree published on September 4th, 1943.
Trials of the experimental prototype of the 122 mm D-25 tank gun took place at the factory proving grounds from September 16th to September 23rd, 1943, when the gun fired 96 shots. The prototype was permitted to continue trials, and was sent to factory #100 in Chelyabinsk on September 25th for installation into an IS tank.
During trials, the D-25 muzzle brake was deformed. Due to the immediate need to install the D-25 gun in a tank, the prototype was sent to factory #100 with the deformed muzzle brake.
On October 10th, 1943, a new reinforced muzzle brake similar to the type used on the German Ferdinand assault gun was built and tested on a D-2 gun with six increased power shots. Another identical muzzle brake was tested on a D-2 gun with 39 shots, 30 of which were increased power, and 9 of which were regular. After checking the muzzle brakes against the reference, neither of them had any deformations. A new reinforced muzzle brake for the D-25 gun will be sent to the GANIOP on October 13th separately, as the tank with the D-25 gun was sent to the GANIOP from factory #100 on October 11th, 1943.
Regional GAU engineer, Engineer-Colonel Abramov."