Miller, that's what is confusing. I know the plug gage size is correct. I make them from aluminum and have them from .722-.732 to use in barrels that have dents in them. Once I find the right size that won't fit through to dent, I make a steel tapered plug that fits under the dent and then tap it snug under the dent and gently tap the outside until the plug gage slides through until I get the right size to bore.
The Skeet's gage with the dial coincides with the readings taken from the breech end of .728 and .729 with the aluminum plug gage of .728 that only goes to 9 7/8". Naturally I cannot get a .724 into the muzzle end and why the Skeets gage reads .718 for 12" is beyond me. I am going to make a .717 plug and try that from the muzzle end and then from the breech end. If there is clearance(light)around it I will then know it is bigger in that area, and that the Skeet's gage is doing something different, but why.
