Thanks, interesting thought on temperature influences, I did not consider that.
In another thread I mentioned Spiralock threads. They seem interesting, at least in situations where you can't pull the male portion.
Spiralock Homepage — Spiralock
While it can't compete with stretching the bolt, it seems that it does spread the tension over more threads which should reduce the need for over torquing.
royinidaho also mentioned that the bullet should tend to tighten the barrel, and intuitively that seems to be the case.
I also did not know that manufacturers used a locking sealant...perhaps a version of Loctite I would assume.