I haven't opened it up, but the process isn't that difficult. As for the mechbox, it's just like any other V2 mechbox. Check out www.mechbox.com
. They have tons of video guides, including a full disassembly and reassembly of the TM MP5-J (which this gun is a 100% clone of). And they have a video guide on the upgrade of a V2 mechbox too.