1. There is no need to try and blow up your rifle to "proof" it. The manufacter should have done this already. In the case of Spainish made barrels, most are proof tested before leaving Spain as per Spainish law. A close inspection of your barrel should show at least one proof mark. Typically that proof mark as found on Traditions, CVA, Winchester guns indicate a 10,000 psi proof.
"Readily available, independent data such as found in the Lyman Black Powder Handbook & Reloading Manual, 2nd Ed., written by Sam Fadala, shows that a 100 grain load of Pyrodex pellets pushing a 240 grain Hornady Sabot develops 20,200 PSI—over DOUBLE the pressure the barrel is proofed to. A 3 pellet load, 150 grains of Pyrodex pellets, develops 27,000 PSI. This specific example is found on page 172 of the Lyman book, other examples abound, some with markedly higher pressures."
2. My interest in this topic is academic at best. Personally I would not own such a weapon. The muzzle loaders that I do own are proof tested by the factory to well beyond any load that I would ever shoot. No offense to you and the other owners of such guns but If I did own one I would not use a load that has been proven to even approach the proof tested limits of such barrels much less exceed them.
IMHO
YMMV
