when firing my rifle, i notice that i can only get about 15 rounds off before the magazine is emptied of gas. There are no leaks in my magazine as far as im concerned.I charge each mag for 11 seconds which should be more than enough. Is it the nozzle? Also the bolt does not lock back after the last round is expelled. I suspect the problem lies in the way the mag sits in the magwell or my bolt carrier is worn down. My magazine wobbles quite a bit. Last of all, the gun will not fire in full auto. When i select full auto and fire the first round fires but then the gun stops firing. I have to cock the charging handle for it to shoot another round. If you have any advice on how to fix this problem, please help me out! A part replacement recommendation would be helpful. I will also be posting pics if needed.