My S&W Military & Police, made in 1941 requires some outward pressure (r. to l.) to open the cylinder .. The rod is tight. If I exert a pressure on the cylinder toward the breech end then it opens easily. The cylinder when open can be moved backward and forward a small amount 1/64" - 1/32". My question is are there shims available to keep the cylinder in a "back" position so I don't have to force the cylinder to the rear to open easily.? Any help appreciated.