I bought a stainless steel CMMG .22 conversion for my M&P-15OR about a month ago. I've used it on three range outings firing about 125 rounds each time with no problems. Using my Primary Arms 1-4x30 scope, I've been able to shoot a 25rd mag into an area the size of a half dollar at 35 yds. Today I was shooting nice tight groups through 150 rds. Then all of a sudden the rounds were flying wild. I thought at first my scope loosened up and was rotated. Nope; that was fine. Then I thought I might have canted the rifle, so I paid attention to that; no help. I noticed that the rounds were all over the place. There was no consistency. I noticed also the the holes in the target were the size of .45 cal instead of pin point holes indicating that the rounds may be tumbling. Has anyone else had similar problems? If so, was it due to residue build up? I'm open to suggestions. I've cleaned the rifle and bolt. Hopefully that will help.