I have killed more than a few big Ontario whitetails with 0 and 00 buck out of a 12 bore. Even killed them with#1 buck out of my beloved 16 bores. I shoot the choke that patterns best and keep my shots no longer than 30 yards. Yes there are better choices and yes the math in relation to buck looks really bad, but if you do your part and shoot responsibly it works well. Funny how some guys slam buck shot for deer hunting then carry 12 bores and buck for bear protection. The last comment was aimed at no one in particular just my obs from bear defense threads.
regards, Darryl