So, this could be an awesome deal but i don’t know for sure. This is my buddy’s former gun and he doesn’t remember the brands he used for the internals when he rebuilt it but this is what he told me: Interchangeable up barrel system. Lower: Noveske G&P Upper (short): Vltor w/ Noveske hand guard, recede length barrel and blackout flash suppressor. Upper (long): MUR-1 Vltor He upgraded the gear set, bearings, and the hop and barrel in the longer upper. He rebuilt the gearbox a couple times with aftermarket parts. Wired for Deans. The gun works great I just don’t 100% know what’s in it. $200 includes shipping.