"To the Deputy Chair of the Council of People's Commissars, comrade L.P. Beria
RE: 122 mm HEAT and 152 mm AP-T rounds
I report that in accordance with GOKO decree #3187ss, GAU tested a 122 mm HEAT shell with a V-229 fuse developed by NKV on May 5-7th and a 152 mm AP-T shell with a MD-5 fuse on May 9-10th.
Trials of the 122 mm HEAT shell were performed with the mod. 1938 howitzer and showed the following results:
RE: 122 mm HEAT and 152 mm AP-T rounds
I report that in accordance with GOKO decree #3187ss, GAU tested a 122 mm HEAT shell with a V-229 fuse developed by NKV on May 5-7th and a 152 mm AP-T shell with a MD-5 fuse on May 9-10th.
Trials of the 122 mm HEAT shell were performed with the mod. 1938 howitzer and showed the following results:
- Stock propellant charge #4 can be used to fire the HEAT shell.
- At a 30 degree angle, the shell penetrates a 100 mm plate (K~=2400) 70% of the time (out of 10 trials) and at a 0 degree angle, the shell penetrates 100% of the time (out of 4 trials).
- Firing at terrain at 1000 meters shows flawless work of the V-229 fuse (7 trials).
- The precision of the shell when fired at a target 1000 meters away is acceptable: mean deviation of 0.32 m vertically and 0.18 m horizontally.
- During trials, the ballistic cap fell off once, which indicates that it is held on insufficiently well.
Trials of the 152 mm AP-T shells were performed with the mod. 1937 gun-howitzer and showed the following results:
- The full stock propellant charge less one bundle of cordite can be used, which achieves a muzzle velocity of 600 m/s.
- The shell penetrates 125 mm of composite armour at an angle of 30 degrees at 1000 meters. The robustness of the hull is satisfactory (4 trials).
- The robustness of the bursting charge after firing at 125 mm armour at normal is satisfactory (2 trials).
- When testing the bursting charge against a 125 mm plate at normal (2 trials) and angled at 30 degrees (2 trials), 3 shells exploded after passing through the plate, one failed to explode (the shell penetrated the armour but no explosion was observed, the shell was found intact without explosive filler).
I conclude that the 122 mm HEAT shell for the mod. 1938 howitzer and the AP-T shell for the mod. 1937 gun-howitzer must be swiftly put into production, during which the NKV must pay close attention to attachment of ballistic caps on the 122 mm HEAT shell and ensure that the fuse reliably ensures that the 152 mm shells explode past the armour.
Chief of the Red Army GAU, Colonel-General of Artillery, Yakovlev
May 10th, 1943"