Jing Gong M4 commando airsoft gun upgrades

Jing Gong or better known as JG has released several new designs of AEG metal gearbox models. These airsoft guns come out of the box shooting airsoft bb's 360 to 370 FPS. The hop up unit on these new aeg models is extremely functional. One downfall I have noticed with these is the plastic bushings that come stock, need to be changed out after about 3 months of moderate to heavy use and metal bushings put in. Do to a slightly undersized bore in the mechbox the holes must be slightly enlarged with a dremel bit so they will accommodate standard 6mm oily metal bushings. As of this date I have worked on 9 of these and they all seem to have the same issue. If you put in the metal bushings without doing this the friction will be to great and the gun will not fire. By just adding the bushings, re-shimming and lapping the gears my JG M733 now chronographs at 385 FPS. Find out more airsoft gun upgrade info and view airsoft gun repair photographs at ABZ's Airsoft Gun Repair.Com