ProMag RM40SL 40-Round AR-15 Magazine 5.56/.223 Black Polymer

ProMag's RM40SL is a 40-round magazine designed for AR-15 rifles chambered in .223 Rem/5.56 NATO. It pairs a DuPont Zytel polymer body with over-molded stamped steel feed lips and catch to support durable feeding. The patented anti-tilt roller follower and a spring formed from heat-treated chrome silicon wire are intended to promote consistent function. The magazine is manufactured in the United States.

Key Specifications

• The capacity is 40 rounds.
• Chambering supports .223 Rem/5.56 NATO cartridges.
• Designed to fit AR-15 pattern rifles.
• The body is constructed from DuPont Zytel polymer.
• Finished in black.
• Features over-molded stamped steel feed lips and magazine catch.
• Includes a patented anti-tilt roller follower.
• Uses a spring formed from heat-treated chrome silicon wire.
• Manufactured in the United States.

Engineered for extended capacity and dependable feeding, the RM40SL offers a practical, high-capacity option for range use, training, and duty applications where durability and consistent function are priorities. Its combination of steel-lined feed lips, anti-tilt follower, and a corrosion-resistant polymer body balances reliability with manageable weight for sustained use.