I bought a cyma cm 040c replica almost a year ago.When I played my first game with it it ran well,at the very end of the game it started to spit out BBs.I didnt know what was going on.I later bought higher quality BBs and it seemed to fix the problem,after a month it started acting up again,it just didnt want to push the BBs over the bucking lip.I put in a mosfet and an aluminum o ring nozzle,hoping it would help,because I noticed that a BB would ocassionaly get stuck on the stock nozzle,after taking it apart and reassembling it over 10 times including the gearbox it ran with no issue for 2-3 months and the first game I went to after that period it acted up again and to this day I cant seem to fix it.NOW I noticed that the nozzle alignment is really bad I tried shimming the entire gearbox to fix it and it still failed,and to note every time I reassembled it,it would shoot fine for a few seconds and it would start to misfeed and double feed,I tried different mags but it didnt help,also it didnt matter if it was in full auto or semi.It has a great air seal I know its not under powered,I manually pushed BBs into the bucking ant it would send them flying every time