With a shotgun that has a receiver mounted scope as apposed to a cantalever barrel mounted scope mount I can see the concern in removing the barrel. But with a scope that is mounted on the barrel, as with muzzleloaders, other than changing the bedding ever so slightly, how much could you possibly change the point of impact? At muzzleloader ranges I don't see how this could cause any problems. So I always remove the barrel on my inline to give the whole rifle a thorough cleaning. That black powder residue seems to find it's way into everything. Now for my Hawkins that has no scope, I have always removed the barrel and never had a problem hitting a deer with the next shot. If you leave water between the barrel and the stock you are asking for rust.