Editing Colt AR-15 (section)

===Muzzle devices===
Colt AR-15 rifles most often have a barrel threaded in {{frac|1|2}}″-28 threads to incorporate the use of a muzzle device such as a [[flash suppressor]], [[sound suppressor]] or [[muzzle brake]]. The initial design, the "duckbill," had three tines or prongs and was prone to breakage and getting entangled in vegetation. The design was later changed to close the end to avoid this problem. Eventually, on the A2 version of the rifle, the bottom port was closed to reduce muzzle climb and prevent dust from rising when the rifle was fired in the prone position.<ref name="Wieland2011">{{cite book|last=Wieland|first=Terry |title=Gun Digest Book of Classic American Combat Rifles|date=November 22, 2011|publisher=Krause Publications|location=Iola, Wisconsin|isbn=978-1-4402-3017-2|page=100}}</ref> For these reasons, the US military declared this muzzle device a compensator, but it is more commonly known as the "GI", "A2", or "Birdcage" muzzle device.<ref name="Crawford2003">{{cite book|author=Steve Crawford|title=Twenty First Century Small Arms: The World's Great Infantry Weapons|url=https://books.google.com/books?id=z7nW8LpDOBoC&pg=PA85|access-date=May 28, 2013|year=2003|publisher=Zenith Imprint|isbn=978-0-7603-1503-3|pages=85–86}}</ref> The standard AR15 muzzle device conforms to the STANAG dimensional requirements for firing [[22 mm grenade|22 mm rifle grenades]].