RE: Buckshot for deer??????
I used to use 3" 00 buck out of my Mossberg 500 Imp Cyl and had great success inside of 40+ yards. Most of my shots were during drives where you were stationed for a 20-40 yard shot. It is definitely deadly when done right but I have also seen results of poor judgement shots.
Good luck and play around with some loads before heading afield.
Bob