Almost all of the damage (and resulting excessive endshake) caused at this location is the result of the impact of the cylinder assembly and the end of the yoke barrel during recoil. Other incidental damage and wear here is causeD by dirt, shooting debris, improper or no lubrication, and the inevitable rotation of the cylinder assembly on the yoke from use....whether during dry firing or live firing.
During detonation, as the frame recoils rearward, the cylinder, which is free to move within the necessary gauge (space) provided to the cylinder assembly on the yoke barrel, moves forward, and, along with the weight of the unfired ammunition in the cylinder (which also moves forward), impacts the rear of the yoke barrel causing peening and wear. Forces from this forward movement of the cylinder during recoil are absorbed by the bearing surface at the rear end of the yoke. Some of this forward pressure exerted on the yoke during firing is also exerted (transferred) onto the yoke stem and the yoke retension screw, which hold the yoke rearward. Wear and tear at these interfaces and contact points is inevitable from usage (live firing)......and the rotation of the cylinder during other movements, like dryfiring and opening/closing, for instance.