The ProMag RM40SL is a 40-round magazine designed to fit AR-15 rifles chambered in 5.56mm. It combines a black DuPont Zytel-based polymer body with steel-lined components and an anti-tilt Roller follower.

Its heat-treated chrome silicon wire spring and U.S.-made construction support consistent magazine function for range use and general rifle setup needs.

Key Specifications

• The magazine capacity is 40 rounds.
• It is designed to fit AR-15 5.56mm rifles.
• The listed caliber designation is .223 Remington/5.56 NATO.
• The body material is DuPont Zytel-based polymer.
• The finish and color are black.
• The magazine uses steel-lined construction with over-molded stamped steel feed lips and a magazine catch.
• The follower is a patented anti-tilt Roller follower.
• The spring is formed from heat-treated chrome silicon wire.
• The model is identified as RM40SL Standard.
• The magazine is made in the USA.

With its 40-round capacity, steel-lined design, polymer body, and roller follower, the ProMag RM40SL provides a practical magazine option for shooters maintaining an AR-15 platform chambered in 5.56mm.