Abstract: A detachable magazine for firearms is provided that includes a magazine body having a quad stack region and a transition region and a follower assembly having a follower body, the follower body configured to travel through both the quad stack region and the transition region. The detachable magazine has canted rear walls to accommodate cartridges with a range of lengths.

Abstract: A detachable magazine for firearms is provided that includes a magazine body having a quad stack region and a transition region and a follower assembly having a follower body, the follower body configured to travel through both the quad stack region and the transition region.

Abstract: A selective fire firearm may be provided having a fully automatic open bolt and a semi-automatic closed bolt mode of operation. The firearm may include a trigger group having a trigger prop that ensures that, when the trigger is released in the fully automatic open bolt mode, the bolt carrier stops in an open bolt position held by an open bolt sear. The trigger prop may include a foot that, following a first trigger pull in the fully automatic open bolt mode, slides under and props a rear end of the trigger in a position that allows the open bolt sear to catch the bolt carrier when the trigger is released and propped but prevents the trigger sear from engaging the hammer.

Abstract: A trigger assembly includes a trigger, a transfer bar having a distal end and a proximal end, the distal end of the transfer bar being coupled to the trigger and the proximal end having a step defined therein; and a sear configured to selectively engage the proximal end of the transfer bar.

Abstract: A trigger assembly includes a trigger, a transfer bar having a distal end and a proximal end, the distal end of the transfer bar being coupled to the trigger and the proximal end having a step defined therein; and a sear configured to selectively engage the proximal end of the transfer bar.

Abstract: A firearm includes a receiver body is provided herein having a plurality of barrel-tightening portions with at least one relief recess therebetween and relief recesses defined in the body on either proximal end. The relief recesses and barrel-tightening portions are sized to allow the barrel-tightening portions to be tightened and loosened independently of each other. A barrel assembly is removably coupled to the receiver body.

Abstract: A firearm includes a receiver body is provided herein having a plurality of barrel-tightening portions with at least one relief recess therebetween and relief recesses defined in the body on either proximal end. The relief recesses and barrel-tightening portions are sized to allow the barrel-tightening portions to be tightened and loosened independently of each other. A barrel assembly is removably coupled to the receiver body.

Abstract: A receiver body is provided herein having a plurality of barrel-tightening portions with at least one relief recess therebetween and relief recesses defined in the body on either proximal end. The relief recesses and barrel-tightening portions are sized to allow the barrel-tightening portions to be tightened and loosened independently of each other.

Abstract: A selective fire firearm may be provided having a fully automatic open bolt and a semi-automatic closed bolt mode of operation. The firearm may include a trigger group having a trigger prop that ensures that, when the trigger is released in the fully automatic open bolt mode, the bolt carrier stops in an open bolt position held by an open bolt sear. The trigger prop may include a foot that, following a first trigger pull in the fully automatic open bolt mode, slides under and props a rear end of the trigger in a position that allows the open bolt sear to catch the bolt carrier when the trigger is released and propped but prevents the trigger sear from engaging the hammer.

Abstract: A selective fire firearm may be provided having a fully automatic open bolt and a semi-automatic closed bolt mode of operation. The firearm may include a trigger group having a trigger prop that ensures that, when the trigger is released in the fully automatic open bolt mode, the bolt carrier stops in an open bolt position held by an open bolt sear. The trigger prop may include a foot that, following a first trigger pull in the fully automatic open bolt mode, slides under and props a rear end of the trigger in a position that allows the open bolt sear to catch the bolt carrier when the trigger is released and propped but prevents the trigger sear from engaging the hammer.

Abstract: A selective fire firearm may be provided having a fully automatic open bolt and a semi-automatic closed bolt mode of operation. The firearm may include a trigger group having a trigger prop that ensures that, when the trigger is released in the fully automatic open bolt mode, the bolt carrier stops in an open bolt position held by an open bolt sear. The trigger prop may include a foot that, following a first trigger pull in the fully automatic open bolt mode, slides under and props a rear end of the trigger in a position that allows the open bolt sear to catch the bolt carrier when the trigger is released and propped but prevents the trigger sear from engaging the hammer.