Proof mark questions - 10ga Clabrough SxS

Pukka Bundook · 3rd March 2009, 06:05 AM

Hello Bill,

Been away from here for a while.
(Detached retina)

The marks forward of the barrel flats are provisional proof marks.

The crossed scepteres and such are the Birmingham proof and view marks of the type used between 1813 and 1904.
these proof marks are for black powder.

the 10 in the diamond is the nominal bore, (10-bore)

can't see the marks at the breech-end of flats very well, but it appears to be an 11 on the right barrel, and 11 over 1 on the left.

this denotes the actual bore, and I can't remeber these actual measurements off the top of my head,

but if one barrel is marked 11, it is a little tighter bore than if marked 11 over "1" which is somewhere between 10 and eleven-bore .

here's a quick example of how it works in 12 gauge;

these are all 12-gauge or 12-bore.
marked 13, bore diameter would be .710"
" 13 over 1 " " " .719"
" 12 " " " .729"
" 12 over 1 " " " .740"

So, same applies to a ten-gauge, but I don't remember the actual measurements....Sorry!

I don't see anything that says how much choke, which is normal.
Choke can only really be reckoned by measuring the bore And the constriction at muzzle.
(As in, full-choke is normally .0040" (40 thou) but to know if you have .0040"
constriction, you need to know the bore size before the choke.)
A gunsmith will tell you if he runs his gauges down the barrel.

Very nice looking barrels!

Richard.

3rd March 2009, 06:05 AM	#2
Pukka Bundook Member Join Date: Jan 2007 Posts: 803	Hello Bill, Been away from here for a while. (Detached retina) The marks forward of the barrel flats are provisional proof marks. The crossed scepteres and such are the Birmingham proof and view marks of the type used between 1813 and 1904. these proof marks are for black powder. the 10 in the diamond is the nominal bore, (10-bore) can't see the marks at the breech-end of flats very well, but it appears to be an 11 on the right barrel, and 11 over 1 on the left. this denotes the actual bore, and I can't remeber these actual measurements off the top of my head, but if one barrel is marked 11, it is a little tighter bore than if marked 11 over "1" which is somewhere between 10 and eleven-bore . here's a quick example of how it works in 12 gauge; these are all 12-gauge or 12-bore. marked 13, bore diameter would be .710" " 13 over 1 " " " .719" " 12 " " " .729" " 12 over 1 " " " .740" So, same applies to a ten-gauge, but I don't remember the actual measurements....Sorry! I don't see anything that says how much choke, which is normal. Choke can only really be reckoned by measuring the bore And the constriction at muzzle. (As in, full-choke is normally .0040" (40 thou) but to know if you have .0040" constriction, you need to know the bore size before the choke.) A gunsmith will tell you if he runs his gauges down the barrel. Very nice looking barrels! Richard.