SAFE MAG .308/AR-10 by Cross Armory


  • Fixed magazine locking system for all .308 & AR-10
  • Automatic Magazine Release when upper and lower receivers are separated, no need to push a button
  • QUICK and SAFE fixed magazine release device
  • SAFE MAG .308 prevents the removal of the magazine from your .308 or AR-10 rifle without disassembly of the action when properly installed
  • QUICK, EASY installation
  • RELOAD EASIER when separating the upper from the lower receiver

NOTE: If you are purchasing for a M&P 10, you will need to select the AERO variation AND you will need a spacer to make the fit perfect. Please let us know that you have an M&P 10 at checkout so that we can include the spacer with your order.

SKU: crSM308 Categories: , , Tags: , , ,

Cross Armory’s SAFE MAG .308 is a modification, designed in California, for weapons in regulated states that require fixed magazines. The Cross Armory SAFE MAG .308 works by releasing your magazine instantly when you separate the upper and lower receivers of your .308 or AR-10, without having to press a button.

Cross Armory’s SAFE MAG .308 is intended to be consistent with the fixed magazine laws which state that your weapon must have a “fixed magazine” which has been defined as “an ammunition feeding device contained in, or permanently attached to, a firearm in such a manner that the device can not be removed without disassembly of the firearm action.” The firearm action of an .308 or AR-10 is housed in the upper and lower receivers. Separating the upper and lower receiver to release your magazine disables the firearm action.

Cross Armory’s SAFE MAG .308 also allows for insertion of a new magazine when the upper receiver and lower receiver are closed, without bending or stressing the hardware of the weapon or of SAFE MAG .308.

Cross Armory’s SAFE MAG .308 is a reliable, durable and easy-to-install magazine release. When paired with the Cross Armory’s QUICK PINS .308, magazine changes can be performed efficiently and with a minimum of inconvenience to the user.

Depending on your build, you will need to choose between the AERO & DPMS variations. Please see instructions below on how to measure when choosing between AERO and DPMS if you do not see your model listed here:

The AERO variation will work on the following models: Aero Precision, Anderson AM10, Armalite A4, Christensen DMR-10, Christensen CA TAC 10, Lewis Machine Tool (LMT), M&P 10 (needs extra spacer, please ask for in notes at checkout)

The DPMS variation will work on the following models: Alex Pro 308, Bushmaster BR 308 (may need fine tuning), CMMG MK-3, DPMS LR308, Fulton Armory 308, Jugernaught Tactical Lower, Noveski N6


Determine the width of the base of your upper receiver:

  1. Separate your upper and lower receiver.
  2. Use calipers or measuring tape to determine the width of the base of the upper receiver (measure are of base directly above the trigger)
  3. If the upper width at the base is 7/8″ or 0.875″, choose Aero. If the upper width at the base is 1  1/4″ or 1.25″, choose DPMS.

Measuring for SAFE MAG .308Measuring for SAFE MAG .308 2


Please note: If your .308 has an ambidextrous magazine release, please call us before purchasing. Installation may require an additional spacer.

FAQ – Frequently asked question:

What is the difference between each Safe Mag?

All the Safe Mag’s function the same way, by automatically releasing the magazine when you separate the upper and lower.  The different models (MIL/DPMS/AERO/2) differ in size and shape in order to fit various models of AR-15 and AR-10.
  • Safe Mag MIL-Spec is for MIL – Spec rifles only (not all AR’s are MIL Spec) and automatically drops the mag when you separate the upper and lower receivers.
  • Safe Mag 2 is designed for all AR-15’s and works and functions exactly the same as Safe Mag MIL-Spec, but it’s shape is a bit different so that it will fit on all styles of AR-15 type rifles
  • SafeMag AERO – is for AR-10 rifles that are made in the AERO style and size
  • SafeMag DPMS – is for AR-10 rifles that are made in the DPMS size and shape.

Additional information

308 Size (see measuring instructions in description)

Aero, DPMS