The Cross Armory Safe Mag (brand part no. CRSM) is a magazine locking system built for shooters in regulated states that require a fixed-magazine configuration on an AR-15 or M4. Once properly installed, it prevents the magazine from being removed without disassembling the rifle’s action, satisfying fixed-magazine requirements without permanently altering the platform. The system releases the magazine automatically the moment the upper and lower receivers are separated, which also disables the action, and it allows a new magazine to be inserted while the upper and lower are closed without bending or stressing any hardware. Machined from black aluminum, it’s compatible with Mil-Spec AR-15/M4 rifles only.

Key Specifications

• Functions as a magazine locking system for fixed-magazine compliance.
• Prevents magazine removal without disassembling the action once installed.
• Releases the magazine automatically when the upper and lower are separated, disabling the action.
• Allows inserting a new magazine while the upper and lower are closed, without stressing hardware.
• Compatible with Mil-Spec AR-15/M4 rifles only.
• Machined from aluminum.
• Finished in black.

Frequently Asked Questions

What does the Safe Mag do? It’s a magazine locking system that prevents the magazine from being removed without disassembling the rifle’s action, for fixed-magazine compliance.

How do I reload the magazine with this system installed? Separating the upper and lower receivers releases the magazine automatically; a new magazine can also be inserted while the upper and lower are closed without stressing the hardware.

What rifles is this compatible with? It’s compatible with Mil-Spec AR-15/M4 rifles only.

Buy the Cross Armory Safe Mag Magazine Locking System, AR-15/M4, Black

Fixed-magazine compliance doesn’t have to mean a clunky aftermarket fix, and Cross Armory built the Safe Mag to work cleanly with the rifle’s own takedown pins. Browse our full gun accessories & parts selection and order from our Lubbock, Texas gun shop for fast, direct shipping.