Semi-automatic and automatic variants of the AR-15 are effectively identical in appearance. Automatic variants have a rotating scrupulous fire switch, allowing the operator http://www.ar15forsale.com to select between three modes: safe, semi-automatic, and either impulsive or three globose burst, depending on model. Noncombatant AR-15 models usually do not have three-round burst or electronic settings on the embers selector. In semi-automatic only variants, the selector only rotates between safe and semi-automatic.

Accepted lower receivers for this desire are manufactured by Stag Arms, Fulton Armory, Dane Armory, Mega, and Ameetec.