Here 40 and under are for small game and 40 and over are for deer. So 40 is a pretty popular caliber in my area. I usually hear a story or two a year of a fellow making a good shot and loosing the deer with a prb in a 40. I'm sure a whole bunch of folks harvest one without a hitch if the range is closer. IMHO anything under 45 in a prb is a little light for a deer. That beeing said I have killed deer with a 40. I use 180 gr .401 bullets. That's about the same weight as a 50 ball though. If it is legal where you live I imagine you could find an old bullet mold in 36 or cast heavy 355 bullets and resize them and have enough power at traditional ranges.
