I just awarded myself the dumba$$ award. While I was blaming the brass I overlooked the evident. I was reloading and noticed that the primers were flattened and the headtamps had marks. Took out the micrometer, and found some serious case head expansion. Looks like those loads were WAY too hot for my rifle. Looking back, I can see not just one, but several mistakes I made. When reloading for the contender, I always start low, work my way up and check each shell as I take it out. With the AR, I made one batch, and then I just sat there pulling the trigger, blasting away and having a good time. When I found problem, I blamed the wrong thing.
Live and learn, I'm just glad I didnt blow my dumb head off.