Nice shooting! I've experienced similar problems - several shots in a very tight group (like 1.5" or less at 100 yards) and then for no apparent reason, then next shot is out of the group by 2" or so. There have been times when maybe I flinched a little and could have caused it, but other times I've been sure that I was on target. One of those mysteries, I guess. When I switched to 777 primers from the hotter Federal 209A primers, the problem of these flyers got a lot better, but it still happens sometimes.