Germany
This gun is a squeeze bore 28/20mm AT gun, although it was technically classified as a heavy AT rifle. Squeeze bore works by using the APCR principles, but instead of the soft metal coming off on impact, it is squeezed down by the barrel. This system keeps a higher pressure longer than conventional guns, which allows higher muzzle velocities and penetration. However, it does not allow any other type of round to be fired by the gun.