We set out to make one of the most affordable complete uppers, without sacrificing the integrity of the complete upper, and most important the rifle. The NBS 20" 5.56 Rifle M-LOK Upper Assembly, is a great all around upper, especially for hunting or long-range target practice. With higher velocity and a longer sight radius with this 20" barrel, we wanted to make sure that any shooter could take this out and shoot long distances, reliably. This upper features a 20 NBS Government Contour barrel chambered in 5.56 with a 1:7 twist and a rifle gas system. The government profile is a great way to round out your build and not have an upper too light or too heavy. With the NBS line we wanted to make sure that we used quality products that wouldn't break the bank. This means using a nitrided steel gas block from APOC Armory as opposed to aluminum and using quality internals like one of our classic NBS 20 rifle barrels.Made in the USALifetime WarrantyUpper ReceiverNBS- 7075 Aluminum- Pairs beautifully with any mil-spec lower- M4 FeedrampsBarrelNBS 20" Black Nitride 4150 Steel Government Barrel, 5.56 NATO, Rifle Length Gas System w/ 1:7 TwistGas SystemRifle Length- APOC Armory Nitrided Steel Gas Block- Stainless Steel Rifle Length Gas TubeHandguard15" NBS M-LOK Free Float Handguard- American Made- 6061 Aluminum*Handguard style may varyMuzzle DeviceMil-Spec A2 Birdcage w/ Jet Black Nitride Finish