I haven't done any big game hunting but if I had to pick one gun out of my collection the good ol' Rem 760 in 30-06 would get the job. The problem is I'd have five shots at him and probably three or four of those would be in him before he got 50 yards from me and then it would be how quick could I reload. Hopefully, he would be dead before he got to me. I wouldn't choose my 12 ga since he's so far away to start with.