Another thing might be shoot down from your bottle.
Air up fully then give your tank one quarter turn or so anti-clockwise.
Some air tank regulator pins can form a choke on the air supply if they're screwed into an ASA too tight... The quarter turn will release that pressure on the pin allowing the air to flow less restricted.
The best way to adjust your sear is with no air or paint. Cock the marker, and pull the trigger. If it de-cocks each time your sear height is good, if not, adjust until it does every time... Then try with air...