The Border Patrol by Geissele Automatics is a no-frills AR-platform that retains the mil-spec features of a service rifle. This workhorse of an AR is available in 11.5", 14.5", 16", and 18" barrel lengths, with corresponding gas systems of carbine, mid, and rifle length systems – each of which is made from precipitation-hardened 17-4 stainless steel. The gas tube is held in place by a retaining pin, and the gas block is attached to the barrel by both pin and two set-screws.