At one time a shotgun was all that was legal in large areas here in south Mississippi. My first deer, a nice 9-point, was shot a long time ago with a load of #4 buck out of an Ithaca Model 37. I don't know just how far away he was, maybe a little too far. The three or four follow-up shots were with 00 buck as he was running away. When recovered, after maybe 50 yards, he had one #4 in his heart and one 00 in his rear end. I almost didn't get him. Every deer I've shot since then has been with a rifle or a bow, but some still use shotguns, and an awful lot of deer have been killed with them. Within bow range or a little beyond any load of buckshot or a slug would be very effective. (By the way, my recurve bow range is within 30 yards.)