Patriot Ordnance Factory (POF-USA) manufactures and distributes law enforcement,[1] military and civilian rifles in Phoenix, Arizona, and was the first manufacturer and seller of gas-piston-operated weapon systems on AR-style rifles in the United States.

To address carbon fouling and a short-barreled timing issue related to traditional AR-15s, POF-USA developed the Regulated Short-Stroke Gas Piston System.

[citation needed] Because hot gases are not injected into the upper receiver, carbon fouling in the action is virtually eliminated.

POF-USA's solution to timing problems related to AR-15's with short gas tubes, POF-USA developed precise op-rod/piston geometry and regulated gas pressure to enable rifles and carbines to be properly timed and bolt speeds (cyclic rates) to be precisely controlled, enhancing extraction and feeding reliability, as well as reducing wear and fatigue on critical components.

[4] POF-USA rifles feature NP3™ coatings and hard, corrosion resistant, nitride heat-treated barrels and gas blocks, eliminating any requirement for lubrication.