I grew up on a ranch located half way between Cody, Wyoming and Yellowstone so had many years hunting with stone points. They were jasper, agate, and obsidian and to be honest were poorly crafted as my knapping skills were crude! The points were primarily made from spalls found in chipping grounds. Bear, moose, elk and mule deer were taken with stones and any shaft I could find. Until this fall while hunting black bear in Canada, I never had an animal get away. That was a poorly placed shot that caused that to happen and not because the stone did not do its job. I used a recurve that was not any better than my arrows so had to be very careful to take only close shots that would answer the promise to the animal not to take a bad shot. So my belief is that stones will do very well if you have good placement with a bow strong enough to drive the arrow home! Watcher