In some embodiments, a firearm comprises a lower receiver, a bolt carrier, a buffer sleeve and a buffer. The lower receiver is arranged to support a hammer and an auto-sear. The bolt carrier comprises a body and a striker moveable with respect to the body between a first position and a second position. The buffer sleeve is arranged to contact the bolt carrier and to contact a buffer spring. The buffer sleeve defines an internal cavity and comprises open ends. The buffer is oriented in the internal cavity and extends through the buffer sleeve. The buffer is arranged to contact the striker and move the striker to the second position.

In some embodiments, a firearm comprises a lower receiver, a bolt carrier, a buffer sleeve and a buffer. The lower receiver is arranged to support a hammer and an auto-sear. The bolt carrier comprises a body and a striker moveable with respect to the body between a first position and a second position. The buffer sleeve is arranged to contact the bolt carrier and to contact a buffer spring. The buffer sleeve defines an internal cavity and comprises open ends. The buffer is oriented in the internal cavity and extends through the buffer sleeve. The buffer is arranged to contact the striker and move the striker to the second position.

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.

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.

In some embodiments, a firearm comprises a lower receiver, a bolt carrier, a buffer sleeve and a buffer. The lower receiver is arranged to support a hammer and an auto-sear. The bolt carrier comprises a body and a striker moveable with respect to the body between a first position and a second position. The buffer sleeve is arranged to contact the bolt carrier and to contact a buffer spring. The buffer sleeve defines an internal cavity and comprises open ends. The buffer is oriented in the internal cavity and extends through the buffer sleeve. The buffer is arranged to contact the striker and move the striker to the second position.

In some embodiments, a firearm comprises a lower receiver, a bolt carrier, a buffer sleeve and a buffer. The lower receiver is arranged to support a hammer and an auto-sear. The bolt carrier comprises a body and a striker moveable with respect to the body between a first position and a second position. The buffer sleeve is arranged to contact the bolt carrier and to contact a buffer spring. The buffer sleeve defines an internal cavity and comprises open ends. The buffer is oriented in the internal cavity and extends through the buffer sleeve. The buffer is arranged to contact the striker and move the striker to the second position.