Developed in collaboration with Advanced Armament Corporation and Remington Arms for optimal performance in the .300 AAC Blackout, the Sierra .30 Cal 125 grain HP MatchKing (#2121) is a flat-base projectile built for precision in AR-platform rifles. While designed for the Blackout, it also performs exceptionally well in other .30 Cal AR and bolt-action applications. The custom-engineered jacket is built to withstand midrange .30 Cal velocities while maintaining Sierra's reputation for record-breaking accuracy. Not recommended for general hunting due to limited expansion, though sometimes used for varmint applications. The #2121 became available in January 2012.

• Sierra MatchKing bullets are trusted by both recreational and pro-level shooters
• Known for excellent accuracy and reliability, this ammunition consistently delivers top-tier results