I hate to resurrect this thread, but, yeah, there is always a but, shooting the 36, in the back yard this morning, I shot a plastic 3 quart, Walmart brand, lemonade jug filled with water, at about 10 feet, just to see what would happen, with no thought to this thread.
A .345 ball with a .020 denim patch, powered by 35 gr of old, 3F GOEX, did not penetrate both sides of the jug. There was a fair bulge from the impact of the ball, on the back side of the jug, but no full penetration, which was something of a surprise. The jug was about 5" in diameter.
Some of the comments, above, about hunting deer with a 36 mentioned using pretty heavy charges on steel at long, for the 36, ranges. IF, someone thought deer hunting with a 36 caliber muzzle loading rifle, was a good idea, I do, highly, suggest heavy powder charges, fired at short ranges, for proper penetration.
As an addendum, I usually shoot this rifle into a stack of old magazines and catalogues, at about 20 yards, when practicing in the back yard. That little ball is mangled pretty badly when recovered for re-casting. Penetration is about 5 inches, there, as well.