You shouls de gass the gun, take it aart and make sure that all the hosing inside is intact. Also try replacing the battery I know it sounds stupid but you never know....
changed o-ring and even bottle and it still makes the noise, I've just tried to take it apart and i havent got very far in about 30minutes lol anyone any ideas?
mm dwell on an ion shoulud be set to 20 standard, i got mine on 13 cos i got a fire bolt and QEV,, (both very good upgrades) some one please put me right