Try a 148 gr. wadcutter at about 700-800 fps. The classic .38 Special target loading works great on small game.
That is all you need right there. For small game, you will not find a better projectile than a wadcutter. It punches clean full caliber holes through the game and is extremely effective. I cannot even begin to tell you the amount of big high desert Jackrabbits that I have killed with .38 wadcutters in the 750-800 FPS range.
Normally I actually hunt them with .44 and .45 caliber revolvers but just to do something different, some hunts I will take along a couple of .38s. Loads of fun and it helps alleviate cabin fever after big game season has ended.
These ones below were actually popped with my Model 29 .44 mag:
But still loads of fun and full wadcutters in a .44 Special make for a great small game getter as well.