End shake refers to the lengthwise movement of a revolver cylinder when it is locked into place in the frame. A perceptible movement is reasonable and normal. End shake becomes a real problem when it is bad enough to create a barrel-cylinder gap over about .010" or when it causes misfires.
End shake is normally the result of wear on one or both of the cylinder bearing points, the ratchet at the back or the bushing at the front. (In S&W revolvers, the forward bearing point is at the rear of the cylinder arbor.) In old revolvers, it can be the result of rusting or corrosion.
In extreme cases, end shake is one of the signs of a frame stretched out of shape by the firing of ammunition with pressure beyond the design limits of the revolver.
Jim
