When saved ounces are essential, Criterion-manufactured lightweight contour barrels provide the perfect fit. With an overall weight as low as 1.40 pounds for the 16" model, our pencil contour barrels offer an extremely lightweight configuration allowing for rapid acquisition and maximized mobility. Uniformity of the bore dimension, groove dimension, and twist, along with a finish produced by hand lapping prove to be necessary in enhancing the ultimate accuracy of each match quality barrel. These barrels will accept both .223 Remington and 5.56 NATO ammunition. Also included is an M4 barrel extension.