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. Long barrel life is achieved by hammer forging from FN's proprietary " machine gun barrel" steel and chrome lining. The rifle also features a fully free-floated HodgeDefense-designed wedge lock handguard, a low-profile gas block that is pinned to the barrel, HP/MPI-tested and certifiedbolt and M16-style bolt carrier group for complete reliabilityand performance.