Barrel bore size?

[NSP64]

What is nominal bore size for a 12ga? I measured mine with a T gage and micrometer and it came out .725 right before the screw in choke.

I have some extended choke tubes that were marked 'full steel' and they measured .715?
With a reduction of .010 they would be 'Mod' wouldn't they? Or is it because the are for steel shot that they are not choked as much?

[briang]

IIRC nominal is .729, don't know about the choke.

[NSP64]

That's what I thought .730. I have an IC Steel choke that measures .735!!!

[longbow]

This may help.