Slow motion video of
firing a .50 calibre Black Powder pistol
As can be seen in this short clip, the effects of recoil on the shooter are quite considerable, notice the way his head moves back and forth in such a short time (about a fifth of a second). By using two hands to support the gun, the extra weight of the left hand helps to reduce the amount of muzzle jump and so the gun can be kept under better control than if just one hand were used.
