MK107 MOD 1-M Upper .223 Wylde

MK107 MOD 1-M Upper .223 Wylde

MK116 MOD 1-M Upper 7.62x39

MK116 MOD 1-M Upper 7.62x39

MK107 MOD 1-M Upper 7.62x39


The MK107 MOD 1-M Upper is equipped with the renowned PWS PWS long-stroke piston system, maintaining the reliability that PWS owners have come to trust. This line features a free-float MLOK handguard, forward assist controls, and a design closer to mil-spec standards, catering to civilians and Law Enforcement alike. With fully forged upper and lower receivers, the MK1 MOD 1-M offers a straightforward solution for those seeking a high-value option that delivers unwavering performance in any situation.

What PWS aficionados refer to as the “THE DIABLO”, the MK07 MOD 1-M Upper is perfect for shooters looking for a weapon that offers a short configuration with the power of the 7.62x39 round. Maintaining the shortest barrel length recommended for suppressed use, this compact upper is one of our most popular in the MK107 lineup.

Highlighted Features

  • PWS Long Stroke Piston System: Renowned for reliability and reduced fouling, with adjustable gas settings for optimal performance.

  • Forward Assist Integration: Essential for reliable chambering of rounds, particularly in adverse conditions, ensuring seamless operation and increased reliability for shooters.

  • Suppressor Optimized: Provides enhanced suppressor performance by minimizing back pressure, reducing gas blowback, and optimizing gas flow for a cleaner and more comfortable shooting experience.

  • 7.62x39 Chambering: Meticulously designed for outstanding accuracy and reliability, accommodating 7.62x39 ammunition.

  • Fully Forged Receiver: Forged 7075-T651 Aluminum upper receiver for durability and strength designed to mil-spec standards, ensuring compatibility and familiarity for users.

  • Free-float MLOK handguard:  Offering improved handling and accessory mounting options.

  • PWS Triad 30 Muzzle Device: Expertly mitigates muzzle flash compared to a standard A2 birdcage.

  • Radian Raptor™ Ambidextrous Charging Handle: Ensures smooth operation for both left and right-handed shooters.

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PWS Long-Stroke Piston System

The MK107 MOD 1-M Upper operates on the highly acclaimed PWS Long Stroke Piston System, renowned for its reliability and reduced fouling. The inclusion of a 3-setting Adjustable Gas System allows users to fine-tune gas flow, ensuring optimal performance in diverse shooting conditions. This innovative system not only enhances reliability but also provides adaptability to various ammunition types and environmental factors.

Why Use the Long-Stroke Piston System?

Opting for a Primary Weapons Systems gas piston system over a traditional Direct Gas Impingement (DI) system on an AR-15 can be motivated by several advantages, particularly in terms of safety, cleanliness, and performance, especially when considering the use of a suppressor. Here are key reasons why you might want to choose a PWS gas piston system:

  • Reduced Gas Blowback: In a piston-operated system, like the one offered by PWS, the gas is not directed back into the upper receiver, minimizing gas blowback towards the shooter's face. This design enhances the overall shooting experience, particularly for those who prioritize a cleaner and more comfortable shooting environment.
  • Enhanced Reliability: The piston system typically provides enhanced reliability, especially in adverse conditions or when the rifle becomes dirty. Since the operating components are not exposed to the combustion gases to the same extent as in a DI system, there's less chance of fouling affecting the rifle's function. This can be a critical factor for users who require consistent performance in various environments.
  • Cooler Operating Temperature: The piston system tends to keep the operating components cooler than a DI system, as the hot gases are vented away from the action. This can contribute to prolonged barrel and component life, reducing wear and potential heat-related issues during extended firing sessions.
  • Cleaner Action: PWS gas piston systems contribute to a cleaner overall firearm because the fouling from burnt powder and carbon is not directed into the receiver. This can result in less maintenance and easier cleaning, which is particularly beneficial for users who prefer spending more time shooting than cleaning.
  • Suppressor Use: When using a suppressor, a piston system is often preferred due to the reduced gas blowback and overall cleaner operation. Suppressors inherently increase backpressure, and a piston system helps mitigate this effect, providing a more pleasant shooting experience and minimizing the risk of gas and debris reaching the shooter's face.
  • Adjustable Gas Systems: Many piston systems, including PWS, come with adjustable gas settings. This feature allows users to fine-tune the gas flow to accommodate different ammunition loads, suppressor usage, or adverse environmental conditions. This level of adaptability is valuable for shooters seeking optimal performance under various circumstances. 

Chambered in 7.62x39

Chambered specifically for the formidable 7.62x39 round, the MK114 MOD 1-M Upper boasts a meticulous design tailored to maximize accuracy and reliability with this caliber. Renowned for its potent stopping power and versatility, the 7.62x39 bullet is favored by shooters seeking robust performance in various applications, from hunting to tactical operations. Its larger caliber and energy retention make it particularly well-suited for engagements at moderate ranges, offering increased terminal effectiveness compared to smaller calibers. Whether navigating dense brush or engaging targets in urban environments, the 7.62x39 round provides a compelling option for shooters requiring substantial firepower and reliability in their firearms.

The MK107 Barrel

The use of 41V50 steel in the construction of barrels, such as the 7.75" barrel featured in this rifle, highlights PWS's commitment to providing top-notch performance. 41V50 is a high-quality, chromium-molybdenum-vanadium alloy steel known for its exceptional strength, toughness, and resistance to wear and heat. Our choice of this premium steel demonstrates their dedication to producing barrels that can withstand rigorous use while maintaining accuracy.

By selecting 41V50 steel, we ensure that our barrels offer a harmonious balance between durability and maneuverability. This steel's robust nature contributes to the barrel's longevity, making it well-suited for various shooting scenarios. Whether engaged in tactical operations or recreational shooting, users can rely on the durability of the 41V50 steel to withstand the demands of their chosen activities.

It's worth noting that our commitment to quality extends beyond material selection. The fact that all barrels are manufactured in-house speaks to their meticulous control over the production process. This level of oversight allows us to maintain stringent quality standards, ensuring that each barrel meets our rigid specifications for accuracy, reliability, and overall performance. Ultimately, the combination of 41V50 steel and in-house manufacturing reflects our dedication to providing shooters with barrels that deliver exceptional performance and durability, making them a trusted choice for discerning firearm enthusiasts.

Understanding Twist Rate

Twist rate refers to the rate of rotation a barrel imparts to a projectile as it travels through. It's expressed as a ratio, indicating how many inches the bullet must travel to complete one full rotation. For example, a 1:10 twist rate means the bullet completes one full rotation every 10 inches of barrel travel. Twist rate plays a crucial role in stabilizing the projectile, ensuring it flies accurately and efficiently.

The primary function of the twist rate is to stabilize the bullet in flight. Stability is achieved by preventing the bullet from tumbling or veering off course. Different bullet weights and lengths perform optimally with specific twist rates. Too slow of a twist can result in insufficient stabilization, leading to accuracy issues, while too fast of a twist may overstabilize lighter bullets, impacting their performance.

The 1/10 Twist Rate

For a rifle chambered in 7.62x39mm, which is a common caliber used in rifles like the AK-47, SKS and the MK107, a 1:10 twist rate means that the rifling completes one full rotation every 10 inches along the length of the barrel. This twist rate is considered standard for many firearms chambered in 7.62x39mm.

The 7.62x39mm cartridge typically fires a bullet with a diameter of approximately .311 inches (7.9mm), and the 1:10 twist rate is optimized to stabilize bullets of this size and weight. The 1:10 twist rate strikes a balance between stabilizing lighter and heavier bullets within the typical range of weights found in 7.62x39mm ammunition.

PWS Triad 30 

Crafted as an upgraded iteration of the classic A2 flash hider, the PWS Triad 30 redefines muzzle flash suppression for the AR-15 platform. Engineered with cutting-edge technology and meticulous attention to detail, this flash hider effectively channels and dissipates gases produced during firing, minimizing signature flash in low-light conditions. Its streamlined profile and precision-machined contours enhance both aesthetic appeal and maneuverability, while its high-strength construction ensures durability and reliability in any environment. Experience the pinnacle of performance with the Triad 30, maintaining your tactical advantage and staying one step ahead on the battlefield.

Which muzzle device is the best for you?

Compensator: A compensator is designed to mitigate recoil and muzzle rise, enhancing overall shooter control. It achieves this by directing gases in specific directions to counteract the natural upward movement of the firearm during firing. While compensators can have secondary functions, such as flash suppression, their primary goal is recoil management. The PWS FSC 30 compensator, for example, excels in reducing recoil and features unique port designs to keep flash away from optics and the line of sight.

Flash Hider: A flash hider, such as the PWS Triad 30 is primarily designed to minimize the visible muzzle flash that occurs during firing. It disperses the burning gases produced by the ignited gunpowder, reducing the intensity of the flash. Flash hiders are valuable for maintaining shooter visibility in low-light conditions and for preventing temporary visual impairment that can occur with larger-caliber firearms. However, they don't provide significant recoil reduction.

Muzzle Brake: A muzzle brake, like a compensator, is focused on recoil reduction and muzzle rise control. It achieves this by redirecting gases to counteract the firearm's natural movement during firing. Muzzle brakes are effective in reducing felt recoil but may produce more noticeable side blast and increased noise compared to compensators. They typically do not offer flash suppression as a primary feature.

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Product Manual

Product Manual

Author:Primary Weapons Systems

PWS Product Manual for complete PWS firearms, uppers and lowers