ProMag builds this extended magazine (part no. RM-40) for the AR-15 platform chambered in .223 Remington/5.56 NATO, holding 40 rounds well beyond a standard 30-round magazine for shooters who want more capacity between reloads. It uses an anti-tilt follower designed specifically to keep feeding reliable at the higher round count, since extended magazines put extra demand on the follower and spring to present each round consistently as capacity climbs. At 10.25 inches overall and roughly 0.45 pounds, it’s a straightforward way to add capacity without stepping up to a drum magazine. For ProMag owners of an AR-15, this AR-15 magazine extends range time between reloads.

Key Specifications

• Chambered in .223 Remington/5.56 NATO.
• Holds an extended 40 rounds.
• Fits the AR-15 platform.
• Uses an anti-tilt follower to keep feeding reliable at the higher capacity.
• Measures 10.25 inches in overall length.
• Weighs approximately 0.45 pounds.
• A detachable box magazine.

Frequently Asked Questions

Why does an extended magazine need an anti-tilt follower? Higher capacities put more demand on the follower and spring to present each round consistently; an anti-tilt design keeps feeding reliable.

How many rounds does this hold? An extended 40 rounds.

Buy the ProMag AR-15 40-Round Anti-Tilt Magazine

An anti-tilt follower keeps this ProMag 40-rounder feeding reliably well past standard AR-15 capacity. Order it from our Lubbock, Texas gun shop for fast, insured shipping.