The Primary Weapons Systems MK109 Mod 1-M .300 BLK complete upper pairs a 9.75-inch barrel with PWS’s long-stroke piston system (brand part no. MK1M1U300BLK9). PWS fits a free-float M-LOK handguard, a Radian Raptor ambidextrous charging handle and its FRC two-port compensator, which is suppressor compatible. The upper is forged 7075-T651 aluminum built to mil-spec standards. The piston system is PWS’s answer to fouling in compact .300 Blackout builds. For a builder who wants a compact, piston-driven .300 BLK upper, this MK109 is a ready-to-run option.

Key Specifications

• The chambering is .300 AAC Blackout, a cartridge built for compact barrel lengths and suppressed use.
• The barrel is 9.75 inches long, a compact length that keeps the upper short.
• The gas system is a long-stroke piston, PWS’s design for reliability and reduced fouling.
• The muzzle device is a PWS FRC two-port compensator that tames recoil and muzzle rise.
• The compensator is suppressor compatible and works with the Rearden Atlas mounting system.
• The handguard is a free-float M-LOK design, which improves handling and accessory mounting.
• The charging handle is a Radian Raptor ambidextrous, usable from either side.
• The upper is forged 7075-T651 aluminum built to mil-spec standards for compatibility.
• PWS backs the upper with its VOW, a warranty that covers repair or replacement of defects.

Frequently Asked Questions

Is this a complete upper? Yes. It is a complete AR-15 upper assembly with the barrel, piston system, handguard, compensator and charging handle.

Can I use a suppressor with it? PWS lists the FRC two-port compensator as suppressor compatible and compatible with the Rearden Atlas mounting system.

What warranty does it carry? PWS covers its products under the PWS VOW, which promises repair or replacement of defects.

Buy the Primary Weapons Systems MK109 Mod 1-M .300 BLK Complete Upper, 9.75-Inch

A short, piston-driven upper takes the fouling out of a compact .300 Blackout build. Order it with more AR-15 uppers from our Lubbock, Texas gun shop for fast direct shipping.