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From: Gale McMillan <>
Newsgroups: rec.guns
Subject: Re: Q: Nominal bore dimensions?
Date: 30 Jun 1996 09:11:02 -0400

Baron wrote:

# 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.

Gale McMillan

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