Punch size for different diameters

[Grenadier1758]

The standard diameter for a 12 gauge is 0.725. With a little bit of choke, the bore can be reduced a bit to 0.720. I can't recall if that may be improved cylinder. It will also be between 13 gauge and 12 gauge. Most often associated with 12 gauge shot guns.

 

[Sparkitoff]

why call it a 13ga?

12 gauge is .729 nominal bore up to .735 overbored. Using the balls per pound standard, .720 would be 13 per pound.

 

[Grenadier1758]

Based on my data the diameter of a ball of 13 to the pound is a 0.710 ball. The 0.720 is 13.5 gauge.

 

[Trev]

I'll try to clarify what I tried to say above, but if this doesn't work just ignore it.

I've seen .700 & .710 listed as 13 ga. and I'd round either to ~11/16", which I suggested not knowing that the gun is not a 13ga.

In the op the "the 13-gauge is 18.3" does not say in what units, hence my "?" regarding it.
So if it is in mm then that does translate to 12ga.; hence my question "why call it a 13ga.?"- if it measures 12ga, why not call it 12ga.? (I'd round that 3/4")

Never Mind! I don't want to know.
(I also don't want to know why a set of dimensions would be partly in metric and partly in inches)

 

[Kansas Jake]

Trev, I have a Navy Arms double 12 gauge marked 18.3 by the manufacturer on the underside of the barrels but it measures 13 guage and TOW 13 gauge wads work great in it. Anyway it seems modern imported muzzleloading shotguns sold and in some cases marked 12 may be anywhere from 11-13.

 

[Trev]

Full choke?

 

[Kansas Jake]

Yes. I measured at the chokes and about 3-4 inches down the barrel. I can’t remember the numbers. It was choked to less than .700 and less than .720 farther down the barrels. If I remember the choke was to .680+-.