Maxim defense 5.56 upper - Maxim Defense Industries PDX U.R.G. Mil-Spec Upper Receiver

Awesome upper, rings steel at 100 yards all day. I had ZERO malfunctions using in semi auto and in Echo Mode (Fostech echo sport). I used with an H1 buffer, I may try out an H2 just to slow it down some. I’m buying another in 7.62x39 to build another pistol. This is a great set up when you can’t carry a rifle, I carry mine in a Vertx Commuter XL 2.0 with room to spare. Buy this upper if you want a compact reliable all around fun gun!!!