SU-76-57

"Mounting of a 57 mm mod. 1943 gun on a SU-76M SPG

This project is being designed according to an order from the Artillery Committee and consists of the installation of a 57 mm mod. 1943 ZIS-2 anti-tank gun barrel on the mount from the 76 mm mod. 1942 ZIS-3 gun on the SU-76M SPG chassis.

The ZIS-2 and ZIS-3 have identical semi-automatic systems and breeches.

The main characteristics of the prototype are shown in the table next to those of the SU-76M:

Characteristic	57 mm gun	76 mm gun
Muzzle velocity: High explosive Armour piercing Subcaliber armour piercing	700 990 1270	680 662 950
Shell mass, kg High explosive Armour piercing Subcaliber armour piercing	3.750 3.120 1.780	6.50 6.56 3.02
Rate of fire, RPM	12	10
Maximum gun elevation	17°	15°
Minimum gun depression	-4°	-3°
Horizontal range	+/-15°	+/-15°
Ammunition capacity	60	60
Crew	4	4
Full length of the SPG, mm	5625	5120
Penetration (calculated) Armour piercing shell at 90° 100 m 300 m 500 m 1000 m 2000 m Subcaliber armour piercing shell at 90° 100 m 300 m 500 m 1000 m 2000 m	115 110 106 96 77 175 160 140 120 95	79 76 73 65 48 128 110 92 77 58
Combat weight, tons	10.5	10.5

Trials of the experimental prototype were performed at the Gorohovets artillery proving grounds from May 1st to May 4th of this year in the amount of 270 shots, 107 of them with an increased charge.

After trials, a second variant of the 57 mm SPG was proposed to the Molotov factory, with the following changes:

• Install the 10-T periscopic sight (remove the panoramic sight of the 76 mm mod. 1942 gun).
• Install an electric trigger in the elevation flywheel handle. It is permitted to use mass production components to make the trigger.
• Completely close the fighting compartment in order to protect the crew from bullets and shrapnel (6-8 mm thick roof, 15 mm rear plate).

Currently, GAZ is working on the second variant of the SPG."

CAMD RF 38-11369-492