Elevate Your AR-15: The Knights Armament SR-15 E3 MOD 2 14.5" Upper Receiver Kit – Unparalleled Performance for Serious Shooters

For discerning rifle builders, tactical professionals, and devoted AR-15 enthusiasts seeking the pinnacle of reliability, durability, and performance, the Knights Armament (KAC) SR-15 E3 MOD 2 14.5" Upper Receiver Kit (MPN: 31949, UPC: 819064016120) represents an elite choice. This complete upper receiver assembly is not merely a collection of parts; it's a meticulously engineered system designed to excel in the most demanding environments, providing a significant upgrade or the perfect foundation for a new, high-performance 5.56x45mm NATO carbine build.

Are you asking yourself, "What is the best complete upper receiver for my AR-15 build?", "How can I enhance the reliability and longevity of my rifle?", or "Which AR-15 upper is trusted by military and law enforcement professionals?" Look no further. The KAC SR-15 E3 MOD 2 upper answers these questions with an emphatic demonstration of cutting-edge design and battle-proven technology. Crafted by Knights Armament, a name synonymous with innovation and uncompromising quality in the firearms industry, this upper is ready to transform your shooting experience.

Why Choose the KAC SR-15 E3 MOD 2 14.5" Upper Receiver?

This isn't just another upper. It's an investment in a system built for sustained performance, designed to mitigate common AR-15 weaknesses while enhancing inherent strengths. Whether you're engaging in competitive shooting, participating in intensive tactical training, or require a reliable tool for professional duty, the SR-15 E3 MOD 2 upper delivers. It comes pre-assembled with Knights Armament’s proprietary features that set it apart from standard AR-15 configurations.

Key Engineering Marvels of the SR-15 E3 MOD 2 Upper

The KAC SR-15 E3 MOD 2 upper receiver is distinguished by several proprietary Knights Armament technologies that contribute to its legendary status:

The KAC E3 Bolt System: Redefining Reliability and Longevity

At the heart of the SR-15's robust performance lies the innovative E3 round-lug bolt design. Unlike traditional AR-15 bolts, the E3 bolt features enlarged, rounded locking lugs. This isn't just an aesthetic change; it's a critical enhancement for both function and durability:

• Enhanced Function: The rounded lugs facilitate smoother, more reliable feeding and extraction, reducing friction and wear within the barrel extension. This translates to fewer malfunctions and a more consistent operational cycle.
• Increased Bolt Life: The increased surface area and optimized geometry of the E3 lugs significantly distribute the forces of firing and extraction. This reduces stress concentrations, extending the life of the bolt far beyond the industry standard, making it a truly "military-grade" component built for sustained high-round counts.
• Reduced Cam Pin Wear: The E3 system also redesigns the cam pin interface, minimizing wear on the bolt itself, which is a common failure point in standard AR-15 designs.

For anyone who demands the utmost reliability from their firearm, especially in high-stakes situations where a malfunction can be critical, the E3 bolt system offers unparalleled peace of mind.

The URX4 M-LOK Handguard: A Foundation of Versatility and Strength

The KAC SR-15 E3 MOD 2 upper integrates a free-floated URX4 M-LOK handguard, a testament to modern rifle ergonomics and accessory integration:

• Monolithic Design: The URX4 features a monolithic design where the handguard essentially forms a single, rigid unit with the upper receiver, achieved through its unique attachment method. This enhances overall system rigidity, crucial for maintaining zero with optics and ensuring consistent accuracy.
• M-LOK Versatility: The M-LOK (Modular Lock) system allows for direct attachment of accessories like lights, lasers, grips, and bipods. This system is lighter and more streamlined than traditional Picatinny rails, offering superior modularity without excessive bulk. Users can place accessories exactly where needed, reducing overall weight and improving handling.
• Effective Heat Dissipation: The design of the URX4 also contributes to efficient heat dissipation, preventing heat buildup from affecting barrel harmonics and ensuring comfortable handling during extended firing sessions.
• Enhanced Ergonomics: The slim profile of the URX4 provides a comfortable and secure grip, allowing for greater control and maneuverability.

The 14.5" Chrome-Lined Barrel: Precision, Durability, and Balance

The heart of any rifle is its barrel, and the KAC SR-15 E3 MOD 2 features a 14.5-inch 5.56mm NATO chrome-lined steel barrel with a 1:7" twist rate:

• Optimal Length for Maneuverability: The 14.5" barrel length strikes an excellent balance between ballistic performance and maneuverability. It's shorter than a standard 16" barrel, making it ideal for close-quarters combat (CQB), vehicle operations, and faster transitions, while still offering sufficient velocity for effective engagement at moderate distances.
• Chrome Lined Durability: The chrome lining inside the barrel bore and chamber provides exceptional resistance to wear and corrosion. This significantly extends barrel life, especially under sustained firing, and makes cleaning easier, a critical factor for rifles used in harsh conditions or with high round counts.
• 1:7" Twist Rate: This twist rate is optimized to stabilize a wide range of 5.56mm NATO and .223 Remington bullet weights, particularly the heavier, more ballistically efficient projectiles (62gr, 77gr, etc.) commonly used by military and tactical shooters. This ensures superior accuracy and terminal performance across various ammunition types.
• Military Grade Construction: Reflecting Knights Armament’s heritage, the barrel is manufactured to military-grade specifications, ensuring it can withstand the rigors of combat and extreme training.

Important Legal Note for Civilian Users: A 14.5" barrel on an AR-15 requires the muzzle device to be permanently attached (pinned and welded) to achieve an overall barrel length of at least 16 inches to comply with National Firearms Act (NFA) regulations, unless the rifle is registered as a Short-Barreled Rifle (SBR). This ensures the weapon remains a legal rifle and not an SBR, avoiding additional registration requirements and wait times. DEGuns can provide guidance or services for compliance.

The KAC 3-Prong Flash Eliminator: Stealth and Suppression Ready

Attached to the 14.5" barrel is Knights Armament’s proprietary 5.56mm 3-Prong Flash Eliminator:

• Superior Flash Suppression: This device is engineered to significantly interfere with propellant gas combustion forward of the muzzle, leading to a dramatic reduction in visible flash signature, especially critical in low-light conditions to preserve night vision and avoid giving away your position.
• Acoustic Properties: Unlike some muzzle devices that can produce an irritating "tuning fork" ring, the KAC 3-Prong is designed not to ring upon firing or when struck, contributing to a more pleasant shooting experience.
• QDC Compatibility: Crucially, this flash eliminator is fully compatible with the Knights Armament line of 5.56mm QDC (Quick Disconnect Coupler) Signature Reduction Devices (suppressors). This allows for rapid and secure attachment of KAC suppressors, enhancing the rifle's versatility for silent operations without needing to change the muzzle device.

Integrated Flip-Up Sights: Ready Out of the Box

The KAC SR-15 E3 MOD 2 upper comes equipped with high-quality, integrated flip-up front and rear iron sights. These provide a reliable backup aiming solution, ensuring your rifle remains operational even if primary optics fail. Their low-profile design ensures they do not interfere with optics mounting.

Who Benefits Most from the Knights Armament SR-15 E3 MOD 2 Upper?

This complete upper receiver kit is ideal for:

• The Discerning AR-15 Builder: If you're constructing a high-end AR-15 and demand top-tier components without compromise, this KAC upper provides a premium foundation. It saves you the hassle of assembling individual parts, guaranteeing factory-level precision and integration.
• Tactical Professionals and Enthusiasts: Law enforcement, military personnel, or dedicated civilian shooters who engage in serious tactical training, competitive shooting, or require a robust rifle for self-defense and preparedness will appreciate the SR-15's proven reliability and performance.
• Reliability-Focused Shooters: Anyone who prioritizes rock-solid reliability, extended component life, and minimal maintenance will find the E3 bolt and chrome-lined barrel invaluable. This upper is built to run, even under adverse conditions.
• Those Seeking a Modernized AR-15: With the M-LOK handguard and suppressor compatibility, this upper positions your AR-15 squarely in the realm of modern, versatile firearm platforms.

The Knights Armament Legacy: A Mark of Excellence

Choosing Knights Armament means choosing a brand with an unparalleled legacy of innovation and service to the United States military and allied forces. KAC is renowned for pioneering advancements in AR platform technology, including the Picatinny rail, free-float handguards, and numerous proprietary improvements. Their products are not just "mil-spec"; they often define the standard against which others are measured, reflecting decades of research, development, and battle-proven performance. When you invest in KAC, you're not just buying a part; you're acquiring a piece of elite firearms engineering.

Optimizing Your AR-15 Experience with KAC

By integrating the Knights Armament SR-15 E3 MOD 2 14.5" Upper Receiver Kit into your build, you are immediately upgrading to a system that delivers:

• Unmatched Durability: Components designed for extreme longevity and resilience.
• Superior Reliability: The E3 bolt system minimizes malfunctions and extends operational life.
• Enhanced Accuracy: Free-floated barrel and quality manufacturing contribute to consistent precision.
• Versatile Customization: M-LOK handguard allows for seamless attachment of modern accessories.
• Combat-Ready Performance: Optimized for flash suppression and suppressor integration.

This complete upper is designed for seamless integration with any standard mil-spec AR-15 lower receiver, instantly transforming your rifle into a high-performance machine. Available at DEGuns, this KAC SR-15 E3 MOD 2 upper is the definitive choice for those who demand the absolute best from their AR-15 platform.

Product Specifications

Feature	Detail
Brand	Knights Armament
Model	Upper Receiver Kit
Caliber	5.56x45mm NATO
Barrel Length	14.50"
Firearm Fit	SR-15 Carbine MOD 2
Gun Platform	AR-Style
Sights	Flip Up Front & Rear
Barrel Finish	Black
Twist Rate	1:7"
Type	Complete Upper
Handguards	URX4 M-LOK
Receiver Material	Aluminum
Barrel Description	Chrome Lined Steel
Receiver Finish	Black
Weight	4 lbs
Handguard Finish	Black
SKU	127170
UPC	819064016120
MPN	31949