Cant figure out caliber of rifle

Puma

Puma

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Buffalo Province.
So I bought a percussion black powder rifle (rifled) on an online auction. It was advertised as a .68 cal.
I won the bid and headed up to the auction house to pick it up. Obviously not a .68 soon as I saw it. Auction house says we know nothing about it, we just sold it. OK.

I bring it home and figured I could gauge the caliber etc.
It is almost exactly like my TC Hawkin in .50 cal. But all the markings have been scrubbed off, reblued, and its in "Precision Grips" after market composite stock and the sights changed to a nice peep sight. Rifling looks good after a proper scrub.

I take it over to a friends place and he mikes the bore, looks to be a .54 cal. Hard to get a consistent reading . I buy a box of Hornady .530 lead round balls.

With one factory TC prelubed .50/.54 .015" patch its pretty loose. I double up the patch and its snug but not too tight. Just about right I'd say. Fired a bunch of balls and accuracy was good at 100 yards.

Doing some quick math, Ball + patch + patch is this maybe a .56 or even a .58 ?

Thoughts ?

Puma
 
Might be other ways, but only way I know to measure a bore is to tap in a slug - so need soft lead thing slightly larger than bore - dribble in light oil into clean barrel - tap that slug in perhaps an inch - and then tap back out from other end - use micrometer to measure the lands - which will be the "high" parts of that slug - is typically the bullet diameter (or close) that you will want. Maybe even one of your round balls - squish it a bit in a vice or tap on metal with a hammer - make it "short and fat" - and tap it in with the fat part as the diameter? On those that I have done, the muzzle peels off the excess lead - use a wood dowel as punch - to NOT want to hit muzzle with a metal hammer. Really is NOT recommended to try to insert long wood dowel into barrel to tap out that slug - want a metal - brass or polished steel that is similar to bore size, to do that part. Is also helpful to wrap electrician vinyl tape around the rod - even a wrap every 6 or 10 inches - to cushion against the rifling and keep that rod more or less centered.
 
Potashminer said:
Might be other ways, but only way I know to measure a bore is to tap in a slug - so need soft lead thing slightly larger than bore - dribble in light oil into clean barrel - tap that slug in perhaps an inch - and then tap back out from other end - use micrometer to measure the lands - which will be the "high" parts of that slug - is typically the bullet diameter (or close) that you will want. Maybe even one of your round balls - squish it a bit in a vice or tap on metal with a hammer - make it "short and fat" - and tap it in with the fat part as the diameter? On those that I have done, the muzzle peels off the excess lead - use a wood dowel as punch - to NOT want to hit muzzle with a metal hammer. Really is NOT recommended to try to insert long wood dowel into barrel to tap out that slug - want a metal - brass or polished steel that is similar to bore size, to do that part. Is also helpful to wrap electrician vinyl tape around the rod - even a wrap every 6 or 10 inches - to cushion against the rifling and keep that rod more or less centered.
Click to expand...

Would be kind of hard to do that without pulling the breech plug.
 
B_noser said:
Would be kind of hard to do that without pulling the breech plug.
Click to expand...

Not at all.
Drop in a chunk of brass rod or steel wrapped in tape. Press or pound the slug in and then tip back and forth so the rod knocks it back out.

Another good way to measure the bore diameter but not grooves is with pin gauges.

A third option would be a cerrosafe cast of the last inch or two of the bore. I'll leave googling that as an exercise for those interested as it's a bit involved.
 
Puma said:
Doing some quick math, Ball + patch + patch is this maybe a .56 or even a .58 ?
Click to expand...

sounds like a 58 (0.530 + 2(0.015+0.015)) = 0.590

The patches will compress a bit - you are probably looking at a 0.570 ball and 0.015 patch. but also sounds like you are doing OK with double patches and smaller ball....
 
Lube the bore to 4" from the muzzle. Hammer in an oversize ball into the bore to 2". Drill a small pilot hole in the ball. Take a 3 or 4" screw and screw it into the ball. Take some vice grips and pull the ball out. Them measure the bore and groove diameter.
 
Why not just eyeball an empty caliper reading at the muzzle? Drop a light down the barrel so you can actually see the rifling and measure the bores lands?
 
Thanks for the suggestions guys.
The rifling does not come right up to the end of the barrel and there is really no crown at the end. The barrel end is finished almost with a roll or ring. This is why its hard to get an accurate inside measurement with a micrometer. I'm thinking its a .58 cal. Maybe a TC Big Boar model. I will look around and see if I can find some .58 round ball . Thx again for all the suggestions.
Puma
 
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