This might be a good place to bring up some info. I've talked to a few barrel manufacturers that say the industry tolerance for bore diameter is 0.0000 to +0.0008". I've played with, not shot, some barrels that are +8 tenths and the reamer at the throat barely makes any contact with the lands. Some manufacturers say barrels will still shoot well at that maximum. Not sure I would want one of those on my gun since I know the few high end barrels I've used have been right on bore diameter. I'm sure this plays into barrel speed as well.