Wednesday 22 March 2017

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."

2 comments:

  1. It looks like the 76mm ZiS-3 APBC penetration estimation is rather optimistic. At least compared to some other 76mm tables posted here earlier. Maybe the BR-350B shell is improved at the date of this paper 6, 7 or 9 / 1944. (The month is hard to read.)

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    Replies
    1. Huh, the penetration is a few mm higher than on my big table. I didn't even notice.

      The date is May. You can see a handwritten note on the last page dated May 31st, 1944

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