The PWS MK1 MOD 2-M is a complete AR-platform upper built around PWS’s long-stroke piston system, chambered in .300 AAC Blackout with a 9.75-inch barrel (PWS part no. MK1-M2U-300BLK-9). The MOD 2-M line adds features exclusive to this generation, starting with PWS’s patent-pending PicLok technology on the free-float handguard, which lets you mount either Picatinny or M-LOK accessories on the same rail. The upper and lower forgings share the same high-end fit and finish PWS is known for, and this line eliminates the forward assist, adds a flared magwell, and builds in a trigger guard among other refinements. This upper ships complete and ready to mate to a compatible AR-platform lower.

Key Specifications

• It is chambered in .300 AAC Blackout, a caliber built for suppressed and short-barrel performance.
• The barrel measures 9.75 inches, matching this specific MK109 configuration.
• It has a 1:8 twist rate, matched to common .300 Blackout supersonic and subsonic bullet weights.
• It uses PWS’s long-stroke piston system rather than direct impingement, for cleaner-running operation.
• The PicLok free-float handguard lets you mount either Picatinny or M-LOK accessories on the same rail.
• It eliminates the forward assist, one of several MOD 2-M-specific refinements.
• It adds a flared magwell for faster magazine changes.
• It ships as a complete upper, ready to mate to a compatible AR-platform lower.
• The upper receiver is forged rather than cast, for a precise, tight fit with the matching lower.

Frequently Asked Questions

Is this upper regulated like a short-barreled rifle? No. This is a bare upper receiver group sold without a lower receiver. Barrel length only becomes an NFA/SBR consideration once the upper is mated to a shouldered rifle-configured lower; paired with a pistol lower or braced pistol build, different rules may apply. Confirm your specific lower configuration meets current ATF rules before assembly.

What operating system does this upper use? It uses PWS’s long-stroke piston system rather than a direct-impingement gas system.

What accessories can I mount on the handguard? The PicLok free-float handguard supports either Picatinny or M-LOK accessories on the same rail.

Buy the PWS MK1 MOD 2-M Complete Upper, .300 BLK, 9.75-inch

Order it directly from our Lubbock, Texas gun shop for fast, insured shipping to your door. Shop the full Primary Weapons Systems lineup and browse our AR15 uppers selection for more build components.