RE: .410 pistol, know of one?
Kirk: when I said you're typically limited to 2.5" shells, I was refering to the BFR and other .410 pistols, which I will not consider the contender to be a pistol in my life. It's a single shot handgun, not a pistol. Personally, buying a handgun cal. contender (unless you're shooting silouettes) seems like a waste of money to me. For the same price, I can get a hunting revolver with 6rnds instead of one.
There's nothing wrong with the "limited power" of the .410. I've hunted upland game, small game, and coyotes all my life with a .410 (not cheap!!), I usually get more game with my .410's than I do with my 12ga's. Not to mention that I'm carrying a gun of about half the weight. With 3" shells, the .410 is a heck of a performer. No, you don't get a lot of shot, so you don't have a huge spread (typically they're pretty tight chokes, as opposed to giving less shot density). I've never had issues with it, but I grew up shooting it. Switching from 12ga to .410 is likely more difficult than the other way around.
Like other's have mentioned, shooting .410's isn't a cheap way to take small game, you've got to love the .410 to own one, because it's going to cost you three times or more to shoot than a 12ga.
I'd suggest you buy a revolver or pistol, any of them would do well really for the circumstances you're describing. Like I said, I hunt rabbits with a .45acp Ruger P-97 quite a bit ($350), a buddy of mine has a Ruger P-89 9mm ($350) and a Hi-point .380auto ($80, yes $80 new. Ugly as a dog's butt, and bulky for a .380, but a workhorse if I've ever shot one) which work quite well for him. I've also got some Ruger Mark II 22lr pistols that work great for that type of hunting, I paid $50 for one of them used. I occasionally take my Ruger Vaquero .44mags out after bunnies too ($415). My fiance uses a Jennings J-22 (fits comfortably in a jeans pocket, but I wouldn't carry it that way) that I bought for $50 new...it's palm sized, I bought it for her as a purse pistol, she hunts rabbits with it!!!