You'll find your automag and pump both work better on air. We have run both and air is just better over the chrono. More stable, less need for c02 expansion bottles etc, just a reg on the bottle and probably one on the marker to keep things well under control. Some of us have been using Sterling pumps with mounted regs to adjust the speed (i.e. keep it under 280) rather than re-spring /washers or fiddle with a dialer. It makes the old school markers just a little more friendly. I love air over C02 and if respected it can be the best propellant out there, but as always, abuse i.e. don't follow the retest rules, don't respect you've high pressure hoses and it will bite you. don't want to scare you off air - far from it - I highly recommend it.