RIFLE: AMERICAN DEFENSE MANUFACTURING MODEL ADM4, SERIAL NUMBER A15-2627, BLUE, CASE NOT INCLUDED, SEMI - AUTOMATIC, 5.56 NATO, 16 Notes: ADM4, 16" barrel, atrius super selector, 5.56, 30+1 ADM4 Equipped with a rosco 16" 1/7 twist 1450 cmv barrel, Geissele automatics mk14 15" handguard, Geissele Trigger that has an atrius super selector installed, and Geissele ambi chargering handle. The ADM4 5.56 is a semi-automatic rifle from American Defense Manufacturing chambered for 5.56 NATO. It uses an AR-style platform with a modular design and is configured with an aluminum receiver set, free-floating handguard, adjustable stock, and direct-impingement operating system. Specific barrel length, furniture, finish, magazine capacity, and other specifications may vary depending on the individual ADM4 configuration.