Supplemental magazine holder for a firearm

A supplemental magazine holder for a firearm, the holder comprising:

• a unitary body having a one-piece construction and being formed from a single piece of resilient material, the body being longitudinally symmetrical about a central axis and having a generally C-shaped cross-section, the body including a base and first and second walls extending upwardly from the base, the base and the first and second walls defining a longitudinal channel extending substantially the entire length of the body between a first closed end and a second open end opposite the first closed end, the channel including opposite first and second inner walls, and each of the first and second inner walls including a longitudinal groove extending substantially along the length of the channel,
• wherein the channel, inner walls and grooves are configured to closely receive and removably retain a firearm magazine inserted longitudinally into the channel through the second open end,
• wherein the first closed end forms a longitudinal stop configured to limit movement of the firearm magazine within the channel,
• wherein the base includes at least two spaced-apart through openings extending through the base, the through openings being configured to receive threaded fasteners extending through the base and engaging corresponding washer elements configured to removably secure the body to a structural rail portion of the firearm, and
• wherein the first and second walls are resiliently deflectable relative to one another to frictionally engage opposite sides of the firearm magazine within the channel, such that the firearm magazine is retained within the channel solely by frictional engagement between the walls and the firearm magazine without clamps, springs, or adjustable fasteners while permitting sliding insertion and removal of the firearm magazine through the second open end.