Look dude, if you want someone to help you need to be patient, and second off, it's not like all of use know exactly what is wrong with your gun so pictures of your problem would help.
Anyways, your gearbox might be a little too high your upper reciever may not be aligned or you just aren't pushing hard enough.
Marshall JCM-2000 + Marshall JCM Cab
JG M733 Enhanced
VFC M4 (not sure which one it started out as)