I believe this is the first full-sized K'nex G3. Props to Barrax for the barrel and hand-guard. Props to MotaBoi for the magazine release. It isn't entirely his, but he gave me the inspiration. And props to Charles Q. Cutshaw for the reference photos. Pros and Cons:
Functional mag release
Ambidextrous charging handle
Front sight is a little off from the real thing
Requires several modified pieces
Flimsy grip and stock (This is both a pro and a con, because it makes the gun more comfortable)
Long trigger pull
If you want instructions, just ask.