Like the Pistoleer, I had mine rechambered. I chose the .284 Winchester.
I had the best luck with a 130gr Sierra Single Shot Pistol bullet and 31.5 grs of H335 with a Federal match primer. This load is a bit above any listed data that I currently see, so you'd be well advised to start at 28 grs and work your way up. A second choice would be the Nosler 140gr BT with 30grs of the same powder. Again, you need to work up. There where some other powders that gave a little bit more velocity, but the accuracy was not as good. Of course 1/2 moa 5-shot groups are not really needed with a 200 yard pistol when hunting is the game.
I've found the extra 700fps with 140's to be handy for longer range shooting. SSK did my rechamber and the accuracy is not diminshed in the least bit from the original chambering. You'll want a external bolt catch installed if you do it though, otherwise you can't unload the pistol as the cartridges are too long when you've got the bullets seated out for 2800fps with a 140gr bullet from the factory barrel.
