From: Gale McMillan <email@example.com>
Subject: Re: Q: Nominal bore dimensions?
Date: 30 Jun 1996 09:11:02 -0400
# What are typical bore dimensions (bore diameter and groove diameter) one
# would expect to find on a .308 Win or .30-06? What sort of tolerances
# are typically held on standard production arms?
The standard for 30 cal is bore is .300, groove .308 Good custom barrels
are held to less than .0002 but it has become the norm with a lot of
manufacturers to go as much as .ooo5 on eather or both. Bore dimensions
is not critical but an undersized groove of .0005 will show pressure
signs quick when you approach max. .0005 oversized doesn't seem to make
any difference to performance.