Airsoft ᗰᗩᖇᔕᕼᗰEᒪᒪOᗯ explains how he went about with this build in this video... "For the Improvement, I have finally got to work on the Bolt AEG gearbox shell. Since the start, I have had this Bolt AEG to work with. The gearbox shell has been a nightmare from day one. Mostly, align everything when putting the box back together; last time it took multipul tries and a few hours to get it done.