Phoenix Arms suggests ammo rated at 1050-1150 fps (subsonic). I've only put about 100 rounds through one of mine so far and the only malfunction has been one FTE, I've been using Federal bulk pack 1260 fps in it. I have two Phoenix Arms HP22A's, one range kit with both the 3" and 5" barrel (black) and one with only the 3" barrel (nickel). Since they have a lifetime warranty I'm going to use ammo rated at 1260 fps in one and subsonic in the other and see if it really makes a difference in longevity. Of the 7 pistols I have the HP22A's are the most fun to shoot and you can shoot for hours on the 525 bulk pack/$20 worth of ammo. I'm not as good a shot as many people, but the HP22A seems to be pretty accurate for such a cheap gun and is easy to keep on target even during fast fire. Well worth the $120 new price I can buy the 3" barrel version for, or $170 for the range kit. I'm going to run a few hundred rounds of Federal HP ammo in the one I use standard velocity in then switch to Remington HP for a few hundred rounds and see which is most reliable. The only subsonic ammo I currently have is Remington.