I do best with Winchester foster slugs, the cheap ones that are $9 for 15 slugs at Walmart. I never had any penetration problems with them, all exited except for one. The one that didn't exit was shot at 75 yards and he was angling towards me. I broke his left shoulder, then the slug travelled the length of the body then broke the rear right femur and it stopped just under the skin of the right rear leg. After all that bone crushing the slug was still in one piece an it weighed over 90% of the original weight. I shot another at the same distance that was boadside. It broke both shoulders and the spine, before exiting. It continued on and passed through a 3-4" white birch then it made a hole in the dirt. We spent about 20 minutes digging but we never found it. Those slugs are plenty strong enough for bear, good luck hunting.