ProMag RM40 40-Round AR-15 Magazine 5.56/.223 Polymer Black

The ProMag RM40 delivers extended capacity for AR-15 platforms with its 40-round design and proven roller follower system. Built from DuPont Zytel polymer, this magazine provides reliable feeding in both 5.56x45mm and .223 Remington chamberings.

What Makes This Different

The RM40 features ProMag's roller follower technology that reduces friction and binding common in high-capacity magazines. Unlike standard 30-round magazines, the extended body maintains feeding reliability through the full 40-round capacity. The DuPont Zytel construction offers impact resistance superior to basic polymer alternatives while maintaining the lightweight characteristics shooters prefer.

Key Features

• 40-round capacity extends range time and reduces reload frequency
• Roller follower system ensures smooth cartridge feeding throughout capacity
• DuPont Zytel polymer construction resists cracking and deformation
• Compatible with 5.56x45mm NATO and .223 Remington ammunition
• Standard AR-15/M16 magazine well compatibility
• Heat-treated steel spring maintains consistent tension
• Black finish matches most tactical rifle configurations

Range performance shows consistent feeding across various ammunition weights from 55-grain to 77-grain projectiles. The extended capacity proves valuable for competitive shooting disciplines requiring sustained fire, tactical training scenarios, and recreational shooting sessions. The polymer construction handles temperature variations from -20°F to 140°F without compromising function. Drop testing demonstrates the magazine retains structural integrity after repeated impacts on concrete surfaces.

Technical Specs

• Capacity: 40 rounds
• Caliber: 5.56x45mm NATO/.223 Remington
• Material: DuPont Zytel polymer body with steel components
• Follower: Roller-type anti-tilt design
• Spring: Heat-treated steel
• Compatibility: AR-15, M16, and compatible platforms
• Finish: Matte black
• Country of Origin: USA

The RM40 addresses the need for extended capacity without sacrificing the reliability expected from duty-grade equipment. ProMag's manufacturing standards and quality control processes ensure consistent performance across production runs.