The most important thing you can do to gain assurance that your barrel will not burst under normal loading is to have an honest-to-God modern test run on it, to determine whether or not it there are any cracks or seams in the steel.
One of the definitions of "Gun Barrel Quality" steel is that the steel mill does an extra fine job of testing the bar stock to assure that it is sound.
Cracks, seams--whatever are uncommon, but they do exist even in the most expensive steel. Now & again even in those nickel-base Superalloys used for gas turbine engines.
The modern test used for such purposes, or at least the best of them, is known as magnetic particle inspection, usually fluorescent magnetic partical inspection. A popular tradenamed device is "Magnaflux"
A few years ago I had a tour of Remington arms in NY state. They Magnafluxed rifle barrels, and used a somewhat less precise test for each shotgun barrel.
Proof Testing was the best thing people had up until some time in the 20th Century. A proof test is a nice thing to do. But really, all it tells you is that whatever crack may be present is just not large enough to cause the barrel to fail on the first couple of shots. If there is a crack, it is likely to grow just a little with each shot.
The messiest muzzle loading barrel failure I saw was of a barrel type known (at least to some of us) to be susceptible to cracks, perhaps formed during the cold drawing process. The gunmaker proofed the rifle, I'd have to search my records but best I recall was something over 200 grains in that .45. The owner put maybe 200-some shots through it before it came apart, taking most of one hand with it. I looked at one fragment & could see that it had evidence of a crack maybe 2--4" long in it. That piece was rusty, so what convinced that barrel maker (really, his insurance company) to cease advertising such barrels was a lot of small cracks found by the U. of Illinois Professor who was also involved in the suit.
The gun maker had proofed the barrel, which was the best one might expect of a custom maker.
Where my own fingers are concerned I'll take Magnaflux, thank you. Or, more precisely, my latest New Toy has a barrel of Gun Barrel Quality steel, a quality which involves the whole steel making process.
Just for kicks, in 1824 Col G Bomford's Regulations for the Proof and Inspection of Small Arms involved loading the .54 caliber common rifle with 1/28 pound (250 grains) powder and two lead bullets, each 1/32 pound (219 grains weight), with two paper wads each 1/2" long after being well rammed. One wad on the powder, the other on top of the balls. That was the first charge. The second charge was lighter, just 1/32 pound (219 grains) powder, only one bullet, and two wads.
This was done at a time when wrought iron barrels often had long seams either in the original iron skelp, or from incomplete forge welds. Weren't a lot of Magnaflux machines around in '24.
Good fortune to you. Statistics are on your side, only a very few contemporary muzzle-loading barrels burst. But for me, I've seen enough that you may have the statistics, thank you.
Yeah, I am that Pain-in-the-A--, Opinionated (and experienced some four decades) metallurgist.
