Although the BT-7 was based on the Christie Model 1931/40, it was relatively lightly armed for its class. It was armed with one 76 mm gun, 1 76 mm machine gun, and 2 37 mm guns. Additionally, it had a redesigned turret. The turret featured a single 45 mm gun, which was replaced by two additional 45 mm guns nearer the rear of the turret. The tank also had a pair of 7.62 mm machine guns set above the main gun. Although the machine guns were present, they were not used during the combat missions of the BT-7.
Early versions of the Combat Vehicle, Recovery, Heavy Repair Workshop (CV''H''-WZ) were used to excavate and recover the buried T-28 and BT tanks. In contrast to the workshop for the BT-2/5/4 model, the CV''H''-WZ-2 had its cantilever spreader arms replaced with a pair of pivoting spreader arms, that would be cast at once on the way to installation on a T-28 or BT-7.
The ZSU-37 had a main gun that had a rate of fire of 1,650 rds/min, compared to the 1,200 rds/min of the 45 mm AT gun. The gun was capable of penetrating 400 mm of armor at a distance of 1,200 m. The real difference between the ZSU-37 and the 45 mm AT gun was its ammunition. The ZSU-37 could fire up to 1,550 rounds of armor piercing (AP) ammunition, compared to the 600 rounds of high-explosive, high-angle-of-flight ammunition of the 45 mm AT gun. It was possible for the ZSU-37 to fire a single HEAT round, or even a single AP round, without the need for a reload. The ZSU-37 was also much heavier than the 45 mm AT gun. It weighed between 23–25 tonnes, as opposed to the 13 tonnes for the 45 mm AT gun. As it would turn out, these weak attributes would cause an issue as the invasions of the USSR by the Germans intensified. d2c66b5586