Abstract: A firearm includes a quick-change barrel including: (a) at least two barrel-mounting features, each configured to selectively interact with a barrel-receipt feature of the firearm during mounting of the quick-change barrel to a mounting structure of the firearm, or (b) at least one barrel-mounting feature configured to selectively interact with at least two barrel-receipt features of the firearm during mounting of the quick-change barrel to a mounting structure of the firearm. The barrel is selectively mountable to the firearm in at least two orientations depending, per (a), upon which of the at least two barrel-mounting features interact with the barrel-receipt feature or, per (b), upon which of the at least two barrel-receipt fixtures interact with the barrel-mounting fixture.

Abstract: A firearm includes a quick-change barrel including: (a) at least two barrel-mounting features, each configured to selectively interact with a barrel-receipt feature of the firearm during mounting of the quick-change barrel to a mounting structure of the firearm, or (b) at least one barrel-mounting feature configured to selectively interact with at least two barrel-receipt features of the firearm during mounting of the quick-change barrel to a mounting structure of the firearm. The barrel is selectively mountable to the firearm in at least two orientations depending, per (a), upon which of the at least two barrel-mounting features interact with the barrel-receipt feature or, per (b), upon which of the at least two barrel-receipt fixtures interact with the barrel-mounting fixture.

Abstract: A belt-fed firearm includes a top cover that can move in at least two degrees of freedom of motion (surge, sway, heave, roll, pitch, and yaw) that in combination allow movement of the top cover to both clear a peripheral accessory mounted to the firearm (such as optics) and open access to a feed surface to permit loading of cartridges to the feed surface.

Abstract: A firearm includes a sear with a sear tip, the sear movable between a stop-fire position, wherein a discharge mechanism is held by the sear tip against movement that would result in firing of a round, and a fire position, wherein the discharge mechanism is released by the sear tip to permit movement of the discharge mechanism to fire a round. The firearm includes a sear return delay mechanism delaying the return of the sear tip to the stop-fire position from the fire position.

Abstract: A trigger assembly for a trigger housing for a, M249 fully automatic rifle is provided having a switch accessible at the outside of the trigger housing for changing the firing of the rifle between semi-automatic and fully-automatic fire.

Abstract: A trigger assembly for a trigger housing for a, M60 fully automatic rifle is provided having a switch accessible at the outside of the trigger housing for changing the firing of the rifle between semi-automatic and fully-automatic fire.

Abstract: A trigger assembly for a trigger housing for a, M249 fully automatic rifle is provided having a switch accessible at the outside of the trigger housing for changing the firing of the rifle between semi-automatic and fully-automatic fire.

Abstract: A trigger assembly for a trigger housing for a, M60 fully automatic rifle is provided having a switch accessible at the outside of the trigger housing for changing the firing of the rifle between semi-automatic and fully-automatic fire.

Abstract: A trigger assembly for a trigger housing for an M240 Assault Rifle is provided having a switch accessible at the outside of the trigger housing for changing the firing of the rifle between semi-automatic and fully-automatic fire.

Abstract: A trigger assembly for a trigger housing for an M240 Assault Rifle is provided having a switch accessible at the outside of the trigger housing for changing the firing of the rifle between semi-automatic and fully-automatic fire.

Abstract: Eye-to-eye videoconferencing may be carried out through the use of a camera secured to an attachment mechanism. The attachment mechanism removably secures the camera to a screen portion of a display screen such that the camera is disposed between the display screen and a person engaged in videoconferencing. In one embodiment, the attachment mechanism is a suction cup. In one alternate embodiment, the attachment mechanism takes the form of first and second strips of double-sided tape. In another alternate embodiment, the attachment mechanism includes first and second magnets removably secured to front and back sides of a flat panel display. Magnetic force between the first and second magnets removably secures the camera to a screen portion of the flat panel display.

Abstract: Eye-to-eye videoconferencing may be carried out through the use of a motion coupling that positions a strut at least partially across a screen, near the eye level of the viewer. A camera may be mounted on a camera portion of the strut to obtain a video image of the viewer. The motion coupling may permit translation or rotation of the strut to reposition the camera. The motion coupling may be selectively lockable through internal,friction or through the use of a locking device. The camera may be movable along the camera portion via a camera translational coupling.

Abstract: Eye-to-eye videoconferencing may be carried out through the use of a motion coupling that positions a strut at least partially across a screen, near the eye level of the viewer. A camera may be mounted on a camera portion of the strut to obtain a video image of the viewer. The motion coupling may permit translation or rotation of the strut to reposition the camera. The motion coupling may be selectively lockable through internal friction or through the use of a locking device. The camera may be movable along the camera portion via a camera translational coupling.

Abstract: Eye-to-eye videoconferencing may be carried out through the use of a camera secured to an attachment mechanism. The attachment mechanism removably secures the camera to a screen portion of a display screen such that the camera is disposed between the display screen and a person engaged in videoconferencing. In one embodiment, the attachment mechanism is a suction cup. In one alternate embodiment, the attachment mechanism takes the form of first and second strips of double-sided tape. In another alternate embodiment, the attachment mechanism includes first and second magnets removably secured to front and back sides of a flat panel display. Magnetic force between the first and second magnets removably secures the camera to a screen portion of the flat panel display.