Ahh, Bwanna, bolt guns are not a true test. Mechanics are very different due to the small bore size vs. the wall thickness. A large bore double with thin barrel walls near the muzzle will react much differently. And throw in the softer steel of old double rifles vs. 4140 and you have a big difference.

I have shot solid steel bullets down a 50 BMG barrel at 2700 ft/sec with no visible damage, but we are dealing with a very heavy barrel with around 1/2" wall thickness at the muzzle, i.e., 1-1/2" outside barrel diameter at the muzzle, 2" at the chamber.

Yep, this subject has been shot, hung, drawn and quartered, but the meat was left to rot and nothing edible remains. Time to close this thread and patiently wait for scientific test results!!!