As an expedient solution, the 45mm Model 1937 was redesigned with a new, longer barrel, resulting in the 45mm Model 1942. Although it could not penetrate the thicker frontal armour of the improved German tanks of 1943, it could still inflict damage against the lighter side armour.

The Red Army introduced the excellent ZiS-2 57mm anti-tank gun into service in 1941 but its production was abruptly cancelled by Stalin’s cronies owing to intelligence mistakes about German tank armour. Production was revived in 1943 to deal with the heavier German tank armour. The 57mm Model 1943, as seen here, used the same tubular trails as the related ZiS-3 76mm divisional gun, while the Model 1941 used rectangular trails.

The excellent ZIS-2 was, in turn, superseded in 1944 by the semiautomatic 100mm Field Gun M1944 (BS-3). Originally based on a naval design and mounted on a dual-tire split trail carriage, the M1944 fired a 35-pound high-explosive shell to a maximum range of 22,966 yards and an antitank projectile to an effective range of 1,093 yards. With a crew of six, the M1944 was capable of firing up to 10 rounds per minute. Although the 100mm T-12 eventually replaced the M1944 in Soviet service, many remain in use around the world.

The Red Army at the outset of the war in 1941 was armed primarily with a single type of anti-tank gun, the 45mm Model 1937. This was a derivative of the German Rheinmetall 37mm PaK 36, the standard German anti-tank gun of the period, which had been manufactured in the Soviet Union under licence since 1931 as the 37mm anti-tank Model 1930. The Red Army desired a larger calibre both to improve anti-armour performance and so as to have a gun which could fire a useful high-explosive projectile. The German 37mm projectile was too small for a good high-explosive round. It was modified to use the tube of the standard Soviet 45mm Model 1934 tank gun, with suitable strengthening of the trunnion and trails. The 45mm Model 1937 anti-tank gun proved to be a versatile weapon and quite potent for its day. With the advent of the T-34 and KV tanks in 1940-1, and the beginning of the armour race on the Eastern front, its utility in fighting tanks rapidly diminished as the Germans began to uparmour their vehicles. Nevertheless, the 45mm anti-tank gun remained in production through 1944. Although the Red Army recognized its shortcomings, it was cheap to produce and its light weight made it ideal for infantry units where motor traction, and often horses, were absent. By the middle of the war it was more often used in the pre-war infantry gun role, for direct-fire support using high-explosive ammunition rather than the anti-tank role.

The Red Army planned to replace the 45mm anti-tank gun with the new ZiS-2 57mm anti-tank gun in 1941. However, a controversy broke out among the Red Army’s leaders over the purported thickness of German tank armour and its production was cancelled shortly after the outbreak of the war, with only 320 produced, in favour of producing new 85mm and 107mm anti-tank guns instead. As it turned out, German tank armour had been grossly exaggerated and the 85mm and 107mm anti-tank guns were much too large, heavy and expensive. Instead of the excellent 57mm ZiS-2, the Red Army had to make due with the increasingly obsolete 45mm anti-tank gun for the early years of the war.

By late 1942 it was evident that the usefulness of the 45mm Model 1937 anti-tank gun was rapidly diminishing. The capture of German ‘arrowhead’ hyper-velocity armour piercing (HVAP) ammunition led to Soviet adaptation of the technology. Called ‘subcalibre’ rounds by the Red Army, a new round for the 45mm Model 1937 became available in April 1942. The ZiS-2 57mm anti-tank gun was resurrected and put back into series production in June 1943. However, the ZiS-2 was too large and heavy for most rifle divisions which did not have adequate motor or horse transport; as a result, the 45mm gun was modernized by developing a new barrel to give the projectile higher velocity and better penetration.

While not adequate to deal with the heavier German tanks such as the Panther or Tiger, it improved its lethality against the more common PzKPfw IV and StuG III. Production of the 45mm Model 1942 began in 1943, eventually replacing the 45mm Model 1937 anti-tank gun. While not intended for anti-tank fighting, Soviet field artillery, especially the widely used ZiS-3 76.2mm divisional gun, was often called upon to fight tanks. As a result, these units were issued with armour-piercing ammunition that was identical to the types used in contemporary tank guns. In August 1942 a sub-calibre round began to be issued as well. The Soviet Union also copied German-shaped charge (HEAT) ammunition. This was most commonly used with howitzers and low velocity guns, such as the 76mm regimental gun and the M-30 122mm howitzer.

The battle at Kursk was a clear indication of the orientation In German armour development, and the growing numbers of Panther and Tiger tanks made it clear that a more potent weapon than the ZiS-2 57mm anti-tank gun would be needed. As a temporary expedient, some units were formed using 85mm anti-aircraft guns in the anti-tank role. As a long-term solution, work began on both 85mm and 100mm towed anti-tank guns in 1943. Ultimately, the BS-3 100mm anti-tank gun was selected for series production, which began on a limited scale in May 1944. Only 591 of these weapons were produced before the war ended, and only 185 were in troop service in January 1945 at the beginning of the final offensive operations against Germany.

There was considerable experimentation with other anti-tank guns during the war but the only other weapon to reach limited production was the 37mm ChK-Ml Model 1944 anti-tank gun. This was a special lightweight, low-recoil weapon intended for paratrooper operations. A total of only 472 were manufactured in 1944-5 and only 104 were issued to the troops. The Red Army received 63 37mm and 653 57mm anti-tank guns from the US, as well as 636 2pdr anti-tank and 96 6pdr guns from Britain, but none of the types were much appreciated or widely used.