Allegedly, this video shows a Russian T-90 tank firing its 125mm gun. A specialized camera called a Photron, usually used in scientific research, captured the action at 18,000 fps. -via Gizmodo | Photron Website
2A46M Gun is a rapid fire (7 rounds per minute)125 MM smoothbore gun. Equipped with assymetrical recoil dampers, the barrel will recoil only an average of 250-300 millimeters.
Tank should be bouncing, but doesn't budge an inch...