Last Christmas I bought a Maine bear hunt at a charity auction. My Son will be 12 this fall and plan on letting him do this hunt. I have never bear hunted before so I don't know what caliber will work on the lower end of the scale, if it was me it wouldn't be an issue. But don't want something that will kick to hard, but don't want something under powered. Was thinking a 20ga w/ slug, he has one that he has used the last two years turkey hunting. Shooting 3 turkey loads out a full choke. Or he can shoot my 6.5 creedmoor or maybe the 45-70.