To the Chair of the Artillery Committee, Major General of Artillery Hohlov
RE: Modernization of the 45 mm mod. 1937 anti-tank gun
Considering the importance of this task, Molotov factory #172 immediately began the modernization of the 45 mm mod. 1937 AT gun according to specifications in letter #567079 sent on February 4th, 1942.
The modernizations proposed by the factory based on the requirements attached to letter #567079 are as follows:
- Monobloc barrel from OHNZM type steel with a robustness category of 0-70, barrel length of 2855 mm (63.5 calibers), muzzle velocity of 880 m/s, maximum chamber pressure of 3075 kg/cm^2, propellant density of 0.75, and minimum chamber robustness reserve of 1.25.
The breech and semi-automatic mechanisms are unchanged.
- The upper and lower mounts are changed slightly in connection with the changes made to the screw type turning mechanism.
- The recoil brake is unchanged. The trails remain unchanged as well.
- Increase of the barrel length by 27.5 calibers compared to the existing length.
- Robustness category of 0-80.
- Increase of the gunpowder charge by 35 grams.
- Maximum chamber pressure of 3100 kg/cm^2.
- Propellant density of 0.76.
- Minimum robustness reserve of 1.18.
- Muzzle velocity of 920 m/s.
- Penetration of 54 mm of K=2400 armour at 30 degrees at a range of 400 meters.