[Andy]

Originally Posted by Mike Poindexter

Bore diameters vary with maker and era. I have a 1929 LC Smith 16 that measures .646 bores. .650 +- was standard for their pre 1930 era 16 ga guns according to those who know. .662 afterward. Similar thing applies to some Parkers. Early 12 bores typically mic'd .750+- according to research done by AH while later 12's came down to .729. Within those parameters, there is some small variation I have observed of 1-3 thousandths. Outside of that, I would suspect honing, reaming, or backboring depending on the amount. I would not worry about your .665 barrels. Whether factory or honed, its not enough to make a difference IMHO.

Thanks Mike, appreciate it.