I've just stripped down my marker, for the first time, and relised that the feed neck would'nt come unscrew, so after asking it nicely... it did give and it was fine. The problem was a small metal ring around the top of the feedneck thread, it was misshaped and the perious owner must have forced it back on, since it now won't go back on is it fine to leave it off? Also, what the hell is it?