I carry a 12ga loaded with slugs for bears here in AK, but I think all the slugs that I have used expand too readily resulting in poor penetration.
I used BRI slugs that must have been made out of the hardest lead available. The exit holes were always about the same size as the entrance. Recoverd slugs were not expanded at all. This was on deer mind you.
Winchester bought BRI out so I don't know if they changed the lead formula or not.
Brenneke is another with fairly hard lead.
If all else fails cast your own with the hard stuff.
If you're too busy to hunt, you're too busy
I'd recommend using Brenneke slugs. Extremely hard hitting. I use them on Whitetails and let me tell you they always drill straight through. Highly recommend them.
Remington has a copper slug (I think the internal base is filled with lead for weight/shock power). The top is notched to break off into 4 unique copper shrapnel pieces while the heavy base core continues on through your target. I haven't actually tried them, but in theory they seem deadly. Like having 4 large buckshot pellets and 1 big slug all blasting through the animal.
Good luck. Ed Kautz
test the brenneke in your gun of choice! My dad had a shotgun that shot great with brenneke's. Mine has a four foot pattern with them at seventyfive yards. I use federal's and get a four inch pattern at the same distance. Brenneke's are fickle as to gun barrel.
try the copper rem slugs or if you can find them activ slugs (spelled that way) they are pretty good
Type Dixie Slugs into your search engine. All of their slugs from 600 to over 800 grain weights are made of hard cast heat-treated lead alloy. Designed for rifled bores, some can be used in cylinder bore shotguns for close range work.