I have a pistol that shoots the .410/45LC combination. .410 rounds come out of it in a pattern that is roughly 10ft at 10 ft. The 000 Buck loads are certainly potent, but you need to be close. Standard 45 LC loads are just this side of painful, but I reload them down a bit to take the worst of the sharpness out.
I bought this piece, a 2-shot derringer, as a put-it-in-their-chest-and-send-'em-to-where-they're-going weapon. In those days I was worried about meeting with rattlers on the trail (2-legged or otherwise), and wanted a light weapon worn on my pack strap.
I have since given up on this experiment. #6 bird shot will do it a timber rattler at your feet. However, the one time I ran into one, the encounter was over quicker than I could have ever drawn. As to the 2-legged snakes, I finally decided that I'd rather carry a more conventional stainless .357 Mag.
On the other hand, I had a buddy that worked on one of the local suburban police depts. His boss, the chief, used to carry a TC Contender with the .410/45 LC barrel. He kept it loaded with 000 Buck.