This is a Sig 516 piston upper, 2nd generation, with the Midwest Industries hand guard installed, which are lighter, lower-profile, and just way better the stock quad rails. There's about 150-200 rounds through. I just never really got to shoot them and ended up buying PWSs and LWRCs, which I'm sort of regretting. 


 


They're awesome uppers and if you don't know the history you should look it up, but the nutshell is that some of the the HK416 designers got poached by Sig and made an updated 416. They left after that and did one for Caracal which is apparently even cooler but that's beyond the point. Looking for 800.