Runs & fires great has 12" rail. - Radical Firearms 16 in. 5.56 SOCOM Upper Assembly

I added loktite to the two gas block screws, because there was no loktite on these screws. Fired one round only at first, the bolt locked back, and brass casting landed about 4:15 clock position, about 3 ft away from were I was shooting from. Fired one round in another mag, and it did same as above. Then loaded a full 30rd mag, and it fired all of them great, then loaded another 30 mag, and it worked great. Then I added scope and sighted it in at 50 yards with 15 more rounds.I was using a PSA lower with carbine buffer 2.9 oz, and carbine spring. The upper shoots like a dream. I set it to shoot 1" low at 50 yards. I read a couple of reviews that said they had problem firing this upper, make sure to add loktite to gas block screws, and make sure gas block is centered on top of barrel before you tighen down screws. I have bought other uppers that gas block we're loose, and they move when you fire the weapon, so always check before you fire the upper. My upper is purring like a cat, and functioning like it should. I would recommend this upper to anyone, I only paid $215, so jump on this if you can.