Academy Sporting Goods usually has a few in stock, as well as ammo. I found a box of 20 410 Federal 000 handgun shells (2 1/2) at wal-mart for less than $13.
I have the stainless unfluted cylinder 3" chamber 3" barreled Judge. I've done a bunch of ammo testing and without a doubt I'd carry the Federal Personal Defense 000 buck in it. It is a 2.5 inch shell that has 4 pellets. The stuff weighed in on my scale at 268 grains total payload. It crono's around 830 fps from the 3 inch barrel. This stuff patterns well out to about 50 feet. Most pellets stay in the human torso on a target. At 4 yards the pattern is only a couple of inches. If you shoot the federal stuff next to the other loads made for the shotgun, the pattern is night and day difference.
The stuff is copper coated and has a special wad which wad designed for rifled short barrels. Winchester is coming out with a defense buck and ball round for it as well.
I'd use 3 inch 7.5 shot for snakes and it is sufficiently accurate with 45 colt rounds. Though it is not tack driver. I like mine and am probably going to buy the desantis holster for it. They are making holsters finally for both length cyliders.