You might also check your barrel cylinder gap. It should be .006, but you need to check all the gaps. The Monson and Palmer plants did all their cylinder milling in the soft then hardened; this sometimes resulted in a variance in the length of the cylinder, .002 was considered acceptable and you just set on the longest chamber. I used to set it at .005 on the longest and it still gave 1" groups until I had the cylinder honed, when I had to bring it in for some trigger work.