Used Rifle
Tuesday, March 2nd, 2010Why is there difference in exit speeds between a rifle and pistol, having the same ammunition used?
Many rifles and pistols used by coeboys in the Old West used the same ammunition. If the same size of bullet is fired from the pistol, however, its muzzle velocity is less than if fired from the rifle. Why is there a difference in exit speeds?
The longer barrel of the rifle means that the bullet is being accelerated over a longer distance. If you assume a constant acceleration (which isn't quite the case) the velocity formula is
V = sqrt(2*A*L)
(V=velocity, A=acceleration, L=length)
So, with the same assumption, a doubling of the barrel length would result in multiplying the velocity by sqrt(2).