Abstract: A compact action for a firearm including an upper receiver housing incorporating a barrel. A bolt and supporting carrier is positioned within the receiver housing so that the bolt is engaged to a rear receiver end of the barrel in a cartridge chambering position. Guide rods are supported within the housing above the barrel and extend in parallel to a rear located end plate. The carrier includes a carrier key supported by and displaceable along the guide rods between the barrel and a rearward bumper component. A gas tube extends from a forward located gas block overlaying a gas discharge aperture in the barrel to a gas key for actuating the carrier rearwardly following discharge of a ballistic from the barrel. A charging handle is manually displaceable along a slot in the housing for actuating an interior slider component, in turn actuating the carrier key to cycle the carrier and bolt.

Abstract: A magazine for a firearm with a magazine well and a reciprocating bolt. A body of the magazine is engaged within the well and has a top, interconnected front, sides and rear walls, and a bottom defining a cartridge holding interior. A spring supported within the interior contacts the bottom and upwardly biases a follower positioned atop the spring toward an opening in the top, through which the cartridges are loaded into the magazine. A feed tower integrated into the top supports a pair of feed lips positioned along opposed edges defining the opening. An aperture is formed in the top rearward of the feed tower. A rear upward projection of the follower aligns with the aperture and, following discharge of a final cartridge, elevates above the top in order to actuate a separate bolt catch or bolt hold open adaptor to prevent a forward returning motion of the bolt.