Abstract: Described herein is a firearm magazine release lock that permanently fixes a magazine to a firearm. This device requires disassembly of the firearm action and disengagement of this device with a special tool prior to release of the magazine. The device comprises a retractable detent extending from a magazine catch that prevents simple removal of a magazine. This device requires disassembly of the firearm action and disengagement of this device with a special tool prior to release of the magazine. In some embodiments the device couples to a security bolt to prevent removal of the device from the firearm.