The 57-mm anti-tank gun LB-3 was designed in the design bureau of plant number 92. Its prototype was made in the second half of 1946. The LB-3 was supposed to replace the ZIS-2 anti-tank gun.
The LB-3 barrel was manufactured as a monoblock with a two-chamber muzzle brake and a screw-on breech. The vertical wedge breech is taken from the ZIS-2 practically unchanged. Semi-automatic copying (mechanical) type.
The reel is hydropneumatic. Rollback brake is hydraulic. The lifting mechanism is a sector, rotary, screw-type push-type mechanism. There is a sector balancing mechanism and torsion suspension.
For direct fire, the OP1-2 telescopic sight was used; it is also possible to place the basket under the Hertz panorama. The chassis used wheels from GAZ-1 with a modified hub.
At the GAP in October - November 1946, they conducted field tests of the 45-mm PTP LB-3. During field tests, 866 shots were fired from the 1544 shots that were supposed to be fired. At this point, the tests were stopped due to poor extraction of the sleeves, which by the end of the tests reached 50%.
Ballistic data of LB-3, obtained during field tests:
- armor-piercing projectile BR-271 weighing 3, 14 kg (charge weight 1355 g) had an initial velocity of 985 m / s, while the pressure in the barrel bore was 3162 kg / cm2;
- O-271U fragmentation projectile weighing 3, 75 kg (charge weight 925 g) had an initial velocity of 693 m / s, while the pressure in the barrel bore was 1680 kg / cm2. The firing range at a targeting angle of 15 degrees was 6480 meters;
- sub-caliber projectile BR-271P weighing 1.79 kg (charge mass 1685 g) had an initial velocity of 1274 m / s, the pressure in the barrel bore was equal to 3082 kg / cm2.
The system, according to the conclusion of the field test commission, did not survive, and further testing requires constructive improvements. It was also noted that the large mass and large trunk pressure of the LB-3 anti-tank gun create much worse transportation conditions on the battlefield compared to the experimental S-15 and 4-26 systems. This conclusion can be regarded as a death sentence.
Thus, the ballistics of the LB-3 and ZIS-2 anti-tank guns coincided.
Technical characteristics of the light 57-mm anti-tank gun LB-3:
Sample - Plant 92;
Full barrel length - 4340 mm / 76 clb.;
Channel length - 3950 mm / 69, 3 clb;
The length of the threaded part - 3420 mm;
The steepness of the grooves - 30 clb.;
Chamber volume - 2.05 l;
The number of grooves - 24;
Cutting depth - 0.9 mm;
Rifle width - 5.45 mm;
Field width - 2.0 mm;
Shutter weight - 31.0 kg;
Barrel weight with shutter - 334 kg;
Angle of vertical guidance - from -9 ° to + 17 °;
Horizontal guidance angle - 58 °;
Recoil length is normal - 960-965 mm;
Recoil length limiting - 720 mm;
The height of the line of fire - 630 mm;
The length of the tool with the shifted beds - 6250 mm;
The width of the tool with the frames extended - 3860 mm;
The width of the tool with the shifted beds - 1660 mm;
Stroke width - 1500 mm;
Shield thickness - 7 mm;
Wheel diameter - 730 mm;
The weight of the retractable parts is 382 kg;
Oscillating part weight - 461 kg;
Shield weight - 65 kg;
Carriage weight without shield and gun - 406 kg;
System weight in firing position - 818 kg;
Rate of fire - 15-25 rounds per minute;
Carriage speed on the highway - 45 km / h.
