Parker 13 gauge?

[Dean Romig]

Jack, you're confusing 'nominal bore diameters' with chamber diameters. The chamber diameter (slightly tapered) will (almost) always be larger than the bore diameter. The diameters you show are nominal bore diameters.

[Jack Hamner]

Originally Posted by Dean Romig

Jack, you're confusing 'nominal bore diameters' with chamber diameters. The chamber diameter (slightly tapered) will always be larger than the bore diameter. The diameters you show are nominal bore diameters.

Yeah...I'm so confused at this point I think I will just wait until I can get a reliable gunsmith to take measurements for me and come up with a definitive answer. I'm just such an impatient person that I think I can get answers to everything "right now". I guess I'm going to have to learn to be a little more patient!

[Smoothebore]

You're doing good, Jack. Sorry I type so slow, a lot of posts while I was hunting and pecking. Dean is simply stating that the muzzle size has nothing to do with gauge. It's all in the chambered shell.