The FN 15 DMR3 Upper receiver enables you to keepon target for faster shot-to-shot recovery by the combinationof the 18-inch hybrid profile barrel, rifle-length gas system,and SureFire ProComp muzzle brake that greatly reduces both recoil impulse and muzzle rise. At the heart of this upper receiver is the FN hammer forged, 18-inch, 1:8 twist, chrome lined barrel. The barrel has FN's Hybrid profile that provides the stiffness and heat absorption needed for accurate, high volume shooting.