41 or 44 mag should do the trick. Enough horsepower to put them down yet still shoot it well. Between the 2, it's a lot easier to find 44 mag ammo. If you're reloading, no worries. if I was carrying it for hunting, I'd like a 6 or 7.5" barrel with a scope. If I was carrying it as a backup just in case while scouting or whatever, I'd want a shorter barrel that's a little quicker to draw, say 4 or 5". Some guys like those Ruger Alaskans but the barrels are too short for me.