PWS Piston-Driven Carbines

The PWS MK107 (Diablo) SBR was developed specifically for CQB requirements and as a replacement option for the MP5-style weapons.

The cutaway of the MK107 demonstrates the importance of an ultra-reliable package that is as light as possible, with mil-spec forgings used for the upper and lower receiver.

Within the last decade, four great debates raged through the firearms world: the 9mm versus the .45 ACP; the AK versus the AR-15; the 5.56mm versus anything with a larger diameter bullet; and direct impingement (DI) versus piston operation for the AR. The good news is that all of these debates have been settled. Well, not really. But there still is good news: In no small part due to the DI–piston debate, DI ARs are now better than ever, more reliable and durable. Piston-operated ARs have also benefitted, growing in popularity and durability.

One well-established name in the piston AR world is Primary Weapons Systems (PWS) out of Boise, Idaho. I’ve worked with PWS products before and found them top notch. It may be tempting to call PWS a new company, but in actuality it’s been around since 2005, working on AK-47s under the name AK Concepts. During this time, it developed the J-Tac47 muzzle brake for the AK-47 family, but demand soon had the company offering the FSC 556, an AR version of the muzzle brake that also functioned as a flash suppressor. The product line expanded to muzzle brakes for ArmaLite’s AR-10, the HK91 and the FN FAL as well.

In 2006, AK Concepts parlayed its extensive AK-47 knowledge and experience and jumped into the AR DI/piston fray with a piston-driven retrofit AR conversion kit, which immediately became quite popular. Around 2008, AK Concepts became PWS and used its experience with the conversion kit to develop its very own AR rifle. That has culminated into the PWS we know today. First came the 5.56mm rifles, then a 7.62x51mm model and then complete uppers. Knowledgeable shooters and real-time trigger-pullers are drawn to PWS rifles for their reliability, durability and workmanship. Viewed by many as one of the best gas piston systems for the AR-15, the PWS long-stroke system with an adjustable gas block has an operating rod that’s permanently attached to the carrier, preventing carrier tilt as it moves back into the receiver extension. Adding to the anti-tilting is PWS’ anti-tilt buffer tube.

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