It's interesting to see how the patterning moves across the target as you change loads. I think I would check to see if the barrel is showing any signs of being loose in the groove. GM's are usually pretty tight on patterning. I'd tighten everything down before I shot any more patterns. The sight falling apart....bad luck. My own best load is 60 Gr of 3F with a .440 ball unsized and a .010 linen patch in my .45. No wiping between shots and using a spit patch instead of lube.
Rock Lock