This BCA AR-15 complete 5.56 NATO rifle length upper has a 16" M4 contour barrel with a black nitride finish, and features a 1:7 twist rate, with a carbine length gas system. It includes the new 15" MLOK rail, an M4 flat-top billet upper receiver, a BCA bolt carrier group, a flash hider, and a rear charging handle. This 5.56 NATO upper is compatible with any mil-spec AR-15 lower. Shop more 5.56 NATO Uppers! Check out Magazines here! {{widget type="Magento\Cms\Block\Widget\Block" template="widget/static_block/default.phtml" block_id="56"}} *Note - We strive to provide the most accurate photographs of our product. Variations may occur in the skeletonized section of the handguard/flash hider you receive. {{widget type="Magento\Cms\Block\Widget\Block" template="widget/static_block/default.phtml" block_id="42"}}