I believe the reason one wants to get all of the oil out of the barrel prior to shooting is to prevent 'rivelling'. I have to admit, and before I knew any better, to having had shot guns with oil in the barrels, with no ill effect. I know this rivelling effect can occur, I've just never had it happen. My guess is, it happens more likely in guns with thin barrel walls. But, I'm not sure if anyone really knows what causes rivelling for sure.

Socialism is almost the worst.