James, yes I agree on the tooling, but if the barrel was tight beforehand, I can't see it loosening, unless it, maybe, had a lot of rounds through it, and it gradually did it over time from thread stretching. I could see using hot rounds, though, and it happening a lot quicker. However, I wonder what might have happened to the thread, and even with re-tightening, I wonder if it might cause it to prematurely do it again? I'm just wondering what would knock something that tight loose, or what the cause is.