Rifle shooting (with .577 T-rex ammunaton) http://nl.youtube.com/watch?v=CQJSZs-euZU This is just awesome
Some super powerful armor piercing bullet that requires alot of power to be projected long distances thus causing alot of knockback by my guess
.577 is high-power, high-caliber ammo. However, you may see such ammo being fired with little or no recoil - the weapon makes the difference. In this case, the rifle used to shoot is too light for the power of the ammo and is not designed in a way to absorb the recoil.
Here's a guy who tried the same kind of ammo with a pistol......... http://www.youtube.com/watch?v=WrXOuWhsU5M