An ammunition magazine configured to bottom-feed a plurality of ammunition rounds into an upper receiver of a firearm, the ammunition magazine comprising: a magazine housing including: an ammunition reservoir , a proximal guide channel disposed proximal to the ammunition reservoir , a distal guide channel disposed parallel to the ammunition reservoir , and lips disposed on a top surface of the magazine housing , the lips configured to align the ammunition reservoir with a feed ramp of the upper receiver; a spring within the magazine housing ; a floor plate retainer disposed at a bottom end of the spring; a floor plate disposed at a bottom end of the magazine housing and reversibly mated with the floor plate retainer ; and a magazine follower disposed at a top end of the spring, the magazine follower including: a follower protrusion disposed on a superior portion of the magazine follower , and a bolt catch piston disposed at a proximal end of a body portion of the magazine follower and configured to slide along the proximal guide channel of the magazine housing ; characterized by a distal guide piston disposed at a distal end of the body portion of the magazine follower , the distal guide piston having a size and shape complementary to the distal guide channel of the magazine housing and configured to slide along the distal guide channel ; wherein the magazine housing further comprises a storage compartment disposed distal to the distal guide channel . a magazine housing including: an ammunition reservoir , a proximal guide channel disposed proximal to the ammunition reservoir , a distal guide channel disposed parallel to the ammunition reservoir , and lips disposed on a top surface of the magazine housing , the lips configured to align the ammunition reservoir with a feed ramp of the upper receiver; an ammunition reservoir , a proximal guide channel disposed proximal to the ammunition reservoir , a distal guide channel disposed parallel to the ammunition reservoir , and lips disposed on a top surface of the magazine housing , the lips configured to align the ammunition reservoir with a feed ramp of the upper receiver; a spring within the magazine housing ; a floor plate retainer disposed at a bottom end of the spring; a floor plate disposed at a bottom end of the magazine housing and reversibly mated with the floor plate retainer ; and a magazine follower disposed at a top end of the spring, the magazine follower including: a follower protrusion disposed on a superior portion of the magazine follower , and a bolt catch piston disposed at a proximal end of a body portion of the magazine follower and configured to slide along the proximal guide channel of the magazine housing ; characterized by a distal guide piston disposed at a distal end of the body portion of the magazine follower , the distal guide piston having a size and shape complementary to the distal guide channel of the magazine housing and configured to slide along the distal guide channel ; wherein the magazine housing further comprises a storage compartment disposed distal to the distal guide channel . a follower protrusion disposed on a superior portion of the magazine follower , and a bolt catch piston disposed at a proximal end of a body portion of the magazine follower and configured to slide along the proximal guide channel of the magazine housing ; characterized by a distal guide piston disposed at a distal end of the body portion of the magazine follower , the distal guide piston having a size and shape complementary to the distal guide channel of the magazine housing and configured to slide along the distal guide channel ; wherein the magazine housing further comprises a storage compartment disposed distal to the distal guide channel . <EOS>