Weather may have had its hand in the matter as well. I would'nt give in so easily, the two major concerns have already been mentioned, checking the breach plug and possibly floating the barrel. It seems that the barrel was well taken care of and that it was clean and clear. Did you fowl the barrel with a primer before shooting. I hear guys do that all the time and they claim they get better accuracy. I have never done that with my toys and they shoot fine, but guys who swear they can't get things to grouphave said this works well. Your gun can only confirm this. I would give it a try.