Answering questions
The right barrel measures .773 the left .755
I don’t see numbers, other than proof marks, or stars.
I appreciate the comments and advice.
The method to determine the patch and ball combination can be subjective because the patch will compress when started past the muzzle.
Some folks like a smaller ball with a thicker patch, while others like a larger ball with a thinner patch.
And then it's possible to load a bare ball sandwiched between cards and wads, or a combination of both patches and wads.
The patch adds double its thickness to the ball diameter, but it will be compressed when loaded at the muzzle probably by half or more.
Smoothbore "rifles" often get best accuracy from an extremely tight ball & patch combination.
But then there can also be consideration for fouling and swabbing between shots.
If a person has a variety of patch sizes then 2 different patch thicknesses can be combined to obtain the right amount of firm resistance in the bore.
The purpose of patches and wadding is to seal off the hot gases in order to get consistent velocity & results if possible.
A bare ball can work when sandwiched in between wads, but may work better with progressively thicker patches.
.005 patches can be handy for adding slightly more resistance to an otherwise loose ball or combination.
By having .005, .010, .015, .018 pillow ticking, and .020 patches on hand, a person can cover all of the bases for experimenting.
It's nice to have commercial patches with a tight weave so that the patch compression is consistent, without any burning.
Let's say you come across some .69 or .715 balls somewhere and want to try them out.
Then you're all set with patching.