20mm projectile is approximately .787 caliber. Also, 20mm is apparently the entry-level where a weapon in this size moves up from being called a gun to being referred to as a cannon. So there’s that.
20mm categorization is more of a convenient shorthand than a universal rule. 20mm anti-tank rifles were during their heyday known as rifles. A modern example like the Anzio is also known as a rifle.
I was curious, so looked this up:
20mm projectile is approximately .787 caliber. Also, 20mm is apparently the entry-level where a weapon in this size moves up from being called a gun to being referred to as a cannon. So there’s that.
20mm categorization is more of a convenient shorthand than a universal rule. 20mm anti-tank rifles were during their heyday known as rifles. A modern example like the Anzio is also known as a rifle.