Custom G&G ARP556 Takedown with beginner explanations

Hi everyone, today I decided to put my ARP556 back together. I'd briefly decommissioned it for doing low power, but figured I'd up the spring and make it a video. If you have any tech questions regarding the video or generally V2 or V3 pattern gearboxes as used in M4s and MP5s (V2) or AKs and G36s (V3), feel free to leave them below and I'll do my best to help out.