John, if I can make the trophy shoot, I can look at it there. I'm no tuner, but I can strip them and put them back together without too many parts left on the table looking for a home.
The barrel o-rings are only under pressure when a shot is fired.
So the theory about the barrel moving the reg sounds like the most likely candidate I can think of, in which case it's just a case of removing the action from body, and removing the reg, checking the seal and replacing if needed, and bolting it back up.
BFTA/NSRA County Coach
CSFTA Chairman/BFTA Rep