This DPMS Mark 12 AR-15 Barrel is fully chambered and ready to install on an upper receiver. The Mark 12 Barrel features a true5.56x45mm NATO Chamber for use with both commercial and military surplus ammunition, while the 1 in 8" Twist Button Rifling is capable of stabilizing medium to heavy weight projectiles with ease for greater retained energy at distance. The heavy contour barrel is constructed of 416 Stainless Steel and given a Teflon Black protective exterior finish for enhanced corrosion resistance. The 18" Mark 12 barrel features a Rifle Length Gas Port location, offering shooters the smoother recoil impulse that is the hallmark of this gas system length due to the increased gas dwell time and lower gas port pressure. Barrel extension and locator pin are both included and factory installed. Technical Information: Length: 18" Material: 416R Stainless Steel Contour: Heavy Chamber: 5.56x45mm NATO Twist Rate: 1 in 8" Chrome Lined: No Finish: Teflon Black M4 Feed Ramps: Yes Muzzle Thread Pattern: 1/2"-28 Gas Port Location: Rifle Exterior Diameter at Gas Port: 0.750" Weight: 2.65 lbs This one. http://www.midwayusa.com/product/43...contour-1-in-8-twist-18-stainless-steel-black About 100 rounds through it. $150. Comes with gas block. No flash hider.