A semiautomatic shotgun comprising a receiver, a barrel, a forward gas block assembly attached to the barrel, a slider assembly rearward of the gas block assembly extending into the receiver. Upon firing a shotshell the explosive gases in the barrel are diverted through two ports into the gas block assembly, specifically into a pair of lateral pressure relief valves positioned on both sides of the barrel. The pressure relief valves further having a gas pathway from the barrel provided by clusters of holes less than a specific size and on-center with the barrel axis. A piston is forced rearwardly and engages a slider of the slider assembly that is linked to a breech block in the receiver. The breech block loads unfired shells and ejects the fired shells accomplishing the semiautomatic recycling. The dual pressure relief valves actuate to moderate and limit the gas pressure that enters the piston chamber when using shotshells of different power levels thereby providing consistency in the recycling operation. The shotgun assembled with a plurality of retention pins having uniformly sized O-rings.

A gas block for a firearm and a gas block system for a firearm. The gas block includes an upper tube connected to a lower tube. The upper tube includes a first passageway and an aperture through the upper tube opposite the lower tube. The lower tube includes a second passageway configured to receive a barrel of a firearm. A central passageway connects the first passageway to the second passageway. A gas nipple having a central bore is threaded into the central passageway. The gas nipple includes an engagement feature to engage a tool for the rotation of the gas nipple within the central passageway. The tool may be inserted through the aperture in the upper tube. The gas nipple may include a taper at the second end. The first passageway is configured to receive a gas tube, or a piston cup, and the second passageway receives a firearm barrel.

A gas block for a firearm and a gas block system for a firearm. The gas block includes an upper tube connected to a lower tube. The upper tube includes a first passageway and an aperture through the upper tube opposite the lower tube. The lower tube includes a second passageway configured to receive a barrel of a firearm. A central passageway connects the first passageway to the second passageway. A gas nipple having a central bore is threaded into the central passageway. The gas nipple includes an engagement feature to engage a tool for the rotation of the gas nipple within the central passageway. The tool may be inserted through the aperture in the upper tube. The gas nipple may include a taper at the second end. The first passageway is configured to receive a gas tube, or a piston cup, and the second passageway receives a firearm barrel.

Firearms with gas piston assemblies have a receiver defining a passage receiving a reciprocating bolt assembly, a barrel defining a barrel axis and extending from the receiver in a forward direction and defining a barrel gas aperture, a gas block connected to the barrel and defining a piston bore in communication with the gas block bore, a piston assembly having a forward end operably engaged to the piston bore and a rear end operably engaged to the reciprocating bolt assembly, the piston assembly having a piston closely received in the piston bore and having a piston rear end, the piston assembly including an elongated intermediate rod having an intermediate rod forward end registered with the piston rear end and an intermediate rod rear end, and the piston assembly including a rear portion having a forward end registered with the intermediate rod rear end and a rear portion.

Firearms with gas piston assemblies have a receiver defining a passage receiving a reciprocating bolt assembly, a barrel defining a barrel axis and extending from the receiver in a forward direction and defining a barrel gas aperture, a gas block connected to the barrel and defining a piston bore in communication with the gas block bore, a piston assembly having a forward end operably engaged to the piston bore and a rear end operably engaged to the reciprocating bolt assembly, the piston assembly having a piston closely received in the piston bore and having a piston rear end, the piston assembly including an elongated intermediate rod having an intermediate rod forward end registered with the piston rear end and an intermediate rod rear end, and the piston assembly including a rear portion having a forward end registered with the intermediate rod rear end and a rear portion.

Firearms with adjustable gas block regulators have a receiver defining a passage receiving a reciprocating bolt assembly, a barrel defining a barrel axis and extending from the receiver and defining a barrel gas aperture, a gas block connected to the barrel and having a gas block inlet registered with the barrel gas aperture, the gas block defining a gas block bore transverse to the barrel axis and in communication with the gas block inlet, the gas block bore defining a gas block bore axis, the gas block defining a gas outlet in communication with the gas block bore, a regulator closely received in the bore and operable to reciprocate along the gas block bore between at least a first position and a different second position, the regulator defining first and second gas paths having different gas flow characteristics.

Firearms with adjustable gas block regulators have a receiver defining a passage receiving a reciprocating bolt assembly, a barrel defining a barrel axis and extending from the receiver and defining a barrel gas aperture, a gas block connected to the barrel and having a gas block inlet registered with the barrel gas aperture, the gas block defining a gas block bore transverse to the barrel axis and in communication with the gas block inlet, the gas block bore defining a gas block bore axis, the gas block defining a gas outlet in communication with the gas block bore, a regulator closely received in the bore and operable to reciprocate along the gas block bore between at least a first position and a different second position, the regulator defining first and second gas paths having different gas flow characteristics.

A gas tube support system for a gas-actuated firearm contains an annular or bored housing for receipt of a gas tube therein, thereby securing the gas tube during operation of the firearm. At least one or more bores are drilled or formed within the annular or bored housing to provide an impingement of the gas tube as it extends through the annular or bored housing. One or more fasteners are threadedly or otherwise received within a corresponding one of one or more respective bores, thereby securing the gas tube within the annular or bored housing. A gas-actuated firearm containing the gas tube support system is also provided.

A firearm can include a receiver, a bolt, and a gas block. In certain implementations, the receiver and/or barrel extension includes a locking shoulder, a lug-interface region forward of the locking shoulder, and a channel wall that defines a bolt channel and a bolt-lug raceway rearward of the locking shoulder. In some implementations, the bolt includes a bolt lug. The bolt lug can be sized and shaped to slidably engage the bolt-lug raceway. Additionally, the bolt can be positioned within the bolt channel of the receiver. Further, the gas block can be positioned at the lug-interface region. In some implementations, the gas block is rotatable with the bolt lug. In particular implementations, the gas block includes a raceway plug sized and shaped to block the bolt-lug raceway. The gas block can also include a bolt-lug notch sized and shaped to mate with the bolt lug.

A firearm including a barrel, receiver, indirect gas system and an adjustable gas block designed to interface with the indirect gas system is provided. Four indexable positions of adjustment are provided for on the adjustable gas block. Positions of adjustment are selected based on the use of a silencer, use of under-powered ammunition, the presence of un-burnt powder and debris in the host firearms operating system, or if the weapon is being fired under “ideal” circumstances. The provided gas block is designed to function with an indirect gas operating system. Excess gas from the operating system is not vented from the gas block thereby generating excess flash and sound. No tool is required to manipulate the adjustment mechanism of the gas.