ProMag COL21 5rd Flush-Fit AR-15 Magazine .223/5.56

The ProMag COL21 is a flush-fit replacement magazine designed for AR-15 rifles chambered in .223 Rem/5.56 NATO. The magazine body is constructed of heat-treated steel and is built as a low-profile spare or replacement for users seeking minimal protrusion from the magwell. It uses an injection-molded follower and a chrome-silicone wire spring for consistent feeding. This magazine is listed as made in the USA.

Key Specifications

• Holds 5 rounds.
• Chambering is .223 Rem / 5.56x45mm NATO.
• Designed to fit the AR-15 platform.
• Magazine type is flush-fit.
• Model identifier reported as COL21 / Standard.
• Magazine body material is heat-treated steel.
• Uses an injection-molded follower.
• Spring is formed from chrome-silicone wire.
• Reported weight is .31 (units not specified in source data).
• Reported country of manufacture is USA.

Compact and low-profile, the COL21 provides a simple, durable spare magazine option for range use, compliant field setups, or as a service replacement. Its steel construction and chrome-silicone spring are specified to support reliable feeding while maintaining a minimal footprint in the magazine well.