I have a .69 ball that blew a block of concrete apart - shot it back in 1986 or so. The block was 14" x 10" x4" thick. The shot was made at 80 yards with what appeared to be a centre hit. I-too found the ball, flattened out to over 1", cupped slightly back with a crack in the middle. The charge was 165gr. 2F (about 6 drams) for 1,500fps. The largest chunk was about 3" in size.

On Moose,unless a big leg bone is hit, these balls exit, making 2" exit holes. A .375H&H for instance, shooting a factory 300gr. Silvertip will be underneath the hide, generally, on the off side, expanded to about .60 cal. The skin of a big bull is very elastic & that keeps the bullets inside. It is rare to get an exit on broadside shots with less than premium bullets which expand to much smaller sizes. For the .69" ball to exit is amazing.

These large, WW balls penetrate way out of proportion to their sectional densities. They don't need to be hardened further by quenching in water.

Sarg's results on granite (or maybe it's sandstone?) shooting are quite typical. What's really amazing is shooting heavy steel plates at 100 yards - I'm stalking about 1' or 1-1/2" thick by about 12" or more, sqaure. Common modern rifles barely move them with perfect hits, but the big balls make them dance. It really gives one an appreciation for momentum vs. fpe.

It is doubtful a 'standard' lead core modern bullet would do anything buy break up on the surface, making a smaller hole, perhaps a deeper "pock", maybe not. From the range of the rock, I'd not be too concerned with richochets, however, a friend of mine shot a curved armour plate at 20 yards, and the flattened 300gr. Sierra came back and whacked him on the belt buckle. He's 6' 18" tall and about 240, - on impact, he sad down abruptly, leaned over and vomited. The bullet simply made a lead splash on the steel, no indentation at all. how much came back, we don't know - couldn't find it. Good thing it was a soft bullet and not a Barnes X - hard to say what would have happened.