100mm MT-12/T-12

2A19 or T-12 is a Soviet-designed 100-mm anti-tank gun. It was the first anti-tank gun to adopt a smoothbore barrel, and to introduce modern armor piercing shot, like the APFSDS. It uses long projectiles that are more powerful than its caliber suggests. The T-12 served as the primary towed anti-tank artillery in the Soviet and Bulgarian armies from the early 1960s to the late 1980s.