A mount for a firearm has a body having a first clamp configured to engage a first edge of the rail, a jaw movably connected to the body and having a second clamp opposed to the first clamp and operable with the respective clamps to engage respective opposed lateral edges of the rail, a spring biasing the jaw toward the body, and at least a portion of the spring being between the clamps. There may be a pushrod connected to a first one of the body and the jaw and slidably received by the other of the body and the jaw. The spring may be laterally positioned to one side of the pushrod. The spring may be a coil spring having a spring axis offset from a pushrod axis defined by the pushrod.

In some embodiments, a fire control mechanism comprises a hammer, a trigger and a safety. The hammer is rotatable about a hammer axis. The trigger is rotatable about a trigger axis and arranged to contact the hammer. The safety is arranged to interfere with rotation of the trigger. The safety comprises a second portion moveable with respect to a first portion.

In some embodiments, a fire control mechanism comprises a hammer, a trigger and a safety. The hammer is rotatable about a hammer axis. The trigger is rotatable about a trigger axis and arranged to contact the hammer. The safety is arranged to interfere with rotation of the trigger. The safety comprises a second portion moveable with respect to a first portion.

Trigger groups for semi-automatic firearms have a frame, a hammer connected to the frame and movable between a cocked position and a striking position, the hammer being biased toward the striking position, a trigger element connected to the frame and movable by a user between a forward position and a rearward position, a selector connected to the frame and movable between at least a first position and a second position, a disconnector having a hammer engagement facility adapted to selectably engage the hammer, a disconnector control element movable between a first control position and a second control position, the disconnector being operably engaged to the disconnector control element, the disconnector operable to move in a first range of motion when the disconnector control element is in the first control position, and in a second range of motion when the disconnector control element is in the second control position.

Trigger groups for semi-automatic firearms have a frame, a hammer connected to the frame and movable between a cocked position and a striking position, the hammer being biased toward the striking position, a trigger element connected to the frame and movable by a user between a forward position and a rearward position, a selector connected to the frame and movable between at least a first position and a second position, a disconnector having a hammer engagement facility adapted to selectably engage the hammer, a disconnector control element movable between a first control position and a second control position, the disconnector being operably engaged to the disconnector control element, the disconnector operable to move in a first range of motion when the disconnector control element is in the first control position, and in a second range of motion when the disconnector control element is in the second control position.

An operating system for a firearm includes a trigger, a hammer, a disconnector, a pivoting arm, and a lower member. The trigger includes a lower portion, an upper portion, and a trigger pivot. The disconnector includes a lower portion, an upper portion, and a disconnector pivot. The pivoting arm includes a forward protrusion, a pivoting arm opening, and a pin extending through the pivoting arm opening. The lower member includes a lower member opening and a pin hole that is coaxial with the trigger pivot and the disconnector pivot. At least a portion of the trigger and at least a portion of the disconnector are disposed within the lower member opening. Motion of the trigger causes the forward protrusion of the pivoting arm to engage a bolt carrier group and hold the bolt carrier group in an open position.

An operating system for a firearm includes a trigger, a hammer, a disconnector, a pivoting arm, and a lower member. The trigger includes a lower portion, an upper portion, and a trigger pivot. The disconnector includes a lower portion, an upper portion, and a disconnector pivot. The pivoting arm includes a forward protrusion, a pivoting arm opening, and a pin extending through the pivoting arm opening. The lower member includes a lower member opening and a pin hole that is coaxial with the trigger pivot and the disconnector pivot. At least a portion of the trigger and at least a portion of the disconnector are disposed within the lower member opening. Motion of the trigger causes the forward protrusion of the pivoting arm to engage a bolt carrier group and hold the bolt carrier group in an open position.

Provided is a trigger mechanism for a firearm having a receiver with a fire control mechanism pocket and a bolt carrier that reciprocates to pivotally displace a hammer when cycled. It includes a hammer having a sear notch and mounted in the fire control mechanism pocket to pivot on a transverse axis between set and released positions. A trigger member has a sear and is mounted in the fire control mechanism pocket to pivot on a transverse axis between set and released positions. The trigger member has a first surface positioned to be forcibly contacted by the hammer when the hammer is displaced by cycling of the bolt carrier, the contact causing at least in part the trigger member to be forced to the set position. A locking bar is slideably mounted in a support frame and spring biased toward a first position in which the locking bar mechanically blocks the trigger member from moving to the released position, and is movable against the spring bias to a second position when contacted by the bolt carrier reaching a substantially in-battery position, allowing the trigger member to be moved by an external force to the released position.

Provided is a trigger mechanism for a firearm having a receiver with a fire control mechanism pocket and a bolt carrier that reciprocates to pivotally displace a hammer when cycled. It includes a hammer having a sear notch and mounted in the fire control mechanism pocket to pivot on a transverse axis between set and released positions. A trigger member has a sear and is mounted in the fire control mechanism pocket to pivot on a transverse axis between set and released positions. The trigger member has a first surface positioned to be forcibly contacted by the hammer when the hammer is displaced by cycling of the bolt carrier, the contact causing at least in part the trigger member to be forced to the set position. A locking bar is slideably mounted in a support frame and spring biased toward a first position in which the locking bar mechanically blocks the trigger member from moving to the released position, and is movable against the spring bias to a second position when contacted by the bolt carrier reaching a substantially in-battery position, allowing the trigger member to be moved by an external force to the released position.

A firearm operating system includes a housing, a central pivoting member disposed within the housing, a trigger including a portion disposed within the housing and a portion extending outside the housing such that the portion of the trigger within the housing includes a hole and at least one finger that extends in a first direction from the hole. Due to movement of the trigger, the at least one finger presses against the central pivoting member to cause the central pivoting member to rotate.