I hunt black bears every year, and have successfully taken one 99% of the time. The other 1% was due to not shooting because of the presence of cubs , or because the bear was just too small. Shots where I hunt are 30 to 35 yards usually, but I've shot them much much closer ie 5 to 10 yards. Thick forest and a swamp for them to escape into if they are able .54 , .62 and 10 bore are what I use....mainly the 10, but any of these are perfectly capable with a decent load and solid hits. I've never lost a bear . BTW, 100 yards over bait seems rather odd . Is it the possibility of seeing a bear that is reluctant to close the distance where you will be hunting , and perhaps wanting that capability ?