Wow, this is very interesting indeed. Wondering if I could double the charge then put two well-seated balls into this Rice 12ga and a long fuse going into the touchhole to proof it.
I only want to prove it because of the dovetailed tenon I put into the underside, as well as a little booboo where I kinda gouged the underside of the barrel as the drill bit passed it while drilling a lockbolt hole.
If the barrel fails I'll be about 100 yards away hiding in my truck parked behind a building. I'd be sad but I'd be safe.
My 1896 copy of “The Gun and Its Development” by WW Greener has proof tables. Here is one that may be relevant for a smoothbore. 12 bore rifles, according to the table on the previous pages, used a heavier proof bullet and less powder 1509 (.709”) or 1511 gr (.700”) bullet and 278 or 269 gr of powder. Depending on the exact bore size these being .729 or .720”. The British used pretty heavy proof loads compared to some on the continent or so I have read. Thin wall barrels should be measures at certain points before and after proof to assure no issues.
I tape down or staple the fuse to what ever I am using to hold the barrel and tape it and some prime at the vent.
On tapered or swamped barrels they should only be fixed, I generally use a wood block with a C clamp, at breech and muzzle to prevent bending the barrel by clamping. I usually put a wood block behind the breech as well firmly secured. Long tangs are more difficult than hooked breech or short tangs.
Be careful. Proof to YOUR satisfaction. Its unlikely a barrel will fail in proof if made of good steel, its also a test of all threaded joints like breeches, vent liners or nipples.
