MK116 MOD 2-M Upper 7.62x39

MK116 MOD 2-M Upper 7.62x39

MK114 MOD 2-M Upper .223 Wylde (NO COMPENSATOR)

MK114 MOD 2-M Upper .223 Wylde (NO COMPENSATOR)

MK114 MOD 1-M Upper .223 Wylde (NO COMPENSATOR)


The MK114 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 a fully forged upper receiver, the MK1 MOD 1-M offers a straightforward solution for those seeking a high-value option that delivers unwavering performance in any situation.

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.

  • .223 Wylde Chambering: Meticulously designed for outstanding accuracy and reliability, accommodating both .223 Remington and 5.56mm NATO.

  • 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.

  • 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 MK114 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 223 Wylde

Chambered in .223 Wylde, the MK114 MOD 1-M Upper is meticulously designed to offer outstanding accuracy and reliability. This caliber choice allows shooters to seamlessly use both .223 Remington and 5.56mm NATO ammunition, providing versatility without compromising on performance.

Why 223 Wylde?

Choosing a rifle chambered in .223 Wylde offers the best of both worlds for consumers seeking versatility and optimal performance. Developed by Bill Wylde, this chamber design seamlessly accommodates both .223 Remington and 5.56mm NATO ammunition, providing users with a broader range of options. The .223 Wylde chamber resembles the .223 Remington externally but incorporates a slightly longer throat to handle the higher pressures associated with 5.56mm NATO rounds. This design not only ensures compatibility with both cartridge types but also enhances accuracy by accommodating longer, heavier bullets commonly used for precision shooting. In essence, opting for a rifle with a .223 Wylde chamber means enjoying the flexibility to use different types of ammunition without compromising on accuracy, making it an ideal choice for shooters looking for a versatile and high-performing firearm.

The MK114 Barrel

The use of 41V50 steel in the construction of barrels, such as the 14.5" 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 1:8 twist rate means the bullet completes one full rotation every 8 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 1/8 Twist Rate

The 1/8 twist rate is often considered one of the best compromises for a 16-inch AR-15 barrel, providing versatility across a range of bullet weights. This twist rate strikes a balance between stabilizing lighter projectiles, like those commonly found in .223 Remington, and effectively stabilizing heavier, higher ballistic coefficient bullets used in 5.56mm NATO ammunition.

Key Advantages of 1/8 Twist

Versatility: The 1/8 twist accommodates a broad spectrum of bullet weights, making it a versatile choice for various shooting applications.
Accuracy Across Bullet Types: Strikes a balance, providing sufficient stabilization for both lighter and heavier bullets, contributing to overall accuracy.
Optimal for Modern Ammunition: Matches well with the performance characteristics of contemporary .223 Remington and 5.56mm NATO ammunition, offering reliable accuracy.

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Product Manual

Product Manual

Author:Primary Weapons Systems

PWS Product Manual for complete PWS firearms, uppers and lowers