inferno problem
i had an inferno as my first gun . very good they are too, anyway the first thing i,ll asume is that your not getting ball jams and your using an electric hopper, this made a big difference to my inferno,s fast firing.
if you strip the gun down,if you havnt got an exploded diagram arrow precision,s website has one to download. check the rubber stopper behind the velocity adjuster at the back o the gun also the state of the hammer( the heavy lump at the bottom which hits the valve to let the gas in) as long as the body of the gun is not too worn and the cocking handle is straight the gun should fire ok.
if you can afford one a pressure regulator makes them work a lot better too.