Well said, Stan.
Going back to the initial post: If you have a 12ga marked .729 and you measure the bore at .735, it's still in proof. It does show evidence of having been honed, but that's not necessarily a bad thing. Honing the bore but leaving the choke alone is one way of increasing constriction. Harder to put choke back in than to take it out, but that's one way to do it.
Also good points above about patterns varying from one brand of ammo to another. However . . . before you pattern, you need to count pellets. I've examined 1 oz loads of US 6's--supposed to be 225/oz--that range in count from high 190's to about 250. That's obviously going to have an impact on pattern density/percentage.
