Elevate Your AR-15: The Knight's Armament URX 4 10.75" M-LOK Handguard

For serious AR-15 enthusiasts, builders, and professionals who demand uncompromising performance and adaptability, the Knight's Armament Company (KAC) Upper Receiver Extending (URX) 4 rail system stands as a pinnacle of engineering excellence. This 10.75-inch free-floating, hybrid forend is not merely an accessory; it's a fundamental upgrade designed to transform your rifle's capabilities, offering enhanced stability, superior modularity, and a significant reduction in overall weight. When "good enough" simply isn't an option for your firearm, the KAC URX 4 provides the professional-grade foundation you need to build or refine your ultimate AR-15 platform.

Why a Premium Handguard Matters: Precision, Customization, and Durability

The handguard is one of the most critical components of an AR-15, influencing everything from accuracy and handling to accessory integration. Many rifle owners seek to upgrade their factory handguards for several key reasons: to improve precision, to attach a wider array of modern accessories, or to reduce the rifle's overall weight for improved maneuverability and reduced shooter fatigue. The KAC URX 4 directly addresses these needs with its innovative design and robust construction.

A common question among rifle owners is, "What makes a free-floating handguard better?" Unlike traditional handguards that clamp directly to the barrel, a free-floating design, like the KAC URX 4, makes no contact with the barrel itself beyond the barrel nut connection to the upper receiver. This isolation prevents any external pressure or torque from affecting the barrel's natural harmonics during firing. The result? Enhanced accuracy and more consistent shot placement, making it an indispensable feature for precision shooting, competitive applications, or any scenario where repeatable performance is paramount.

Unpacking the KAC URX 4's Advanced Design

The KAC URX 4 sets itself apart with several distinctive features that contribute to its exceptional performance:

The Power of a One-Piece Integral Barrel Nut Construction

One of the most revolutionary aspects of the URX 4 is its unique one-piece construction with an integral barrel nut. Traditional handguards often require a separate barrel nut to be torqued onto the upper receiver, followed by the attachment of the handguard itself. The URX 4 streamlines this process by incorporating the barrel nut directly into the handguard's body. This design offers several critical advantages:

• Unparalleled Stability: By integrating the barrel nut, the URX 4 creates an incredibly rigid and robust connection between the handguard and the upper receiver. This eliminates potential points of flex or loosening that can compromise accuracy or the stability of mounted accessories, ensuring your optics and lasers maintain their zero even under strenuous conditions.
• Simplified Installation (Relatively): While requiring specific KAC tools for proper installation, the integral design simplifies the overall assembly by reducing the number of components. This also means fewer potential points of failure over time, contributing to the handguard's long-term durability.
• Reduced Weight and Bulk: Consolidating the barrel nut into the handguard design contributes to the URX 4's remarkably light overall weight of just 11.4 ounces for the 10.75-inch model. This weight saving is crucial for building a lightweight AR-15, which translates to faster target transitions, less fatigue during extended carrying or shooting sessions, and a more agile rifle system.

M-LOK Modularity: The Future of Accessory Attachment

The KAC URX 4 fully embraces the M-LOK accessory attachment system, a highly popular and effective solution for modern rifle customization. Many users ask, "What are the benefits of M-LOK over Picatinny?" While Picatinny (MIL-STD-1913) rails are robust, they are also heavier and bulkier, often leaving unused rail segments that can snag on gear or feel uncomfortable in hand. M-LOK, on the other hand, offers a sleek, low-profile alternative:

• Enhanced Ergonomics: With M-LOK, accessories can be mounted only where needed, leaving the rest of the handguard smooth and comfortable to grip. The slim profile of the URX 4 (1.55" inside diameter, 1.68" outside diameter) further enhances this ergonomic advantage.
• Significant Weight Savings: M-LOK slots are lighter than full Picatinny rail segments, contributing to the overall lightweight design of the URX 4.
• Direct Attachment: M-LOK allows for direct attachment of accessories via a simple camming action, providing a secure and repeatable connection without the need for bulky adapters. This means your lights, foregrips, bipods, and other essential tools can be mounted exactly where you need them, without adding unnecessary bulk or weight.

Full-Length Picatinny Top Rail: Legacy Meets Modernity

While M-LOK dominates the sides and bottom for modularity, the URX 4 features a continuous, full-length Picatinny top rail. This design choice ensures compatibility with a vast array of existing optics, iron sights, and laser aiming devices that rely on the Picatinny standard. This uninterrupted rail surface allows for flexible optic placement, enabling users to optimize eye relief and accommodate various shooting stances or preferences. For those building a rifle for duty, competition, or critical applications, the reliability and wide adoption of the Picatinny top rail is a non-negotiable feature.

Materials and Finish: Built for the Toughest Conditions

The KAC URX 4 is meticulously crafted from high-quality aluminum, a material chosen for its optimal balance of strength and weight. Aluminum handguards are known for their durability and ability to withstand the rigors of heavy use, impacts, and environmental exposure.

Beyond the base material, the URX 4 undergoes a hardcoat anodizing process, resulting in a tough, durable matte black finish. This anodization isn't just for aesthetics; it provides a crucial layer of protection against corrosion, abrasion, and general wear and tear. It creates a surface that is significantly harder than raw aluminum, ensuring the handguard maintains its integrity and appearance even after years of active service. This commitment to robust materials and finishes is a hallmark of Knight's Armament products, designed to perform flawlessly in demanding real-world scenarios.

Compatibility Considerations: Maximizing Your Build Potential

To fully utilize the benefits of the KAC URX 4, particularly its sleek profile and free-floating design, it requires the use of a low-profile gas block. Standard A2-style front sight posts or larger gas blocks will typically not fit underneath this modern handguard. This is a common requirement for most free-float handguards and allows for a clean, uninterrupted top rail and a more streamlined appearance. When planning your AR-15 build or upgrade, ensuring compatibility with a low-profile gas block is an essential step to achieve optimal performance and aesthetics with the URX 4.

The Knight's Armament Legacy: A Name Synonymous with Innovation

Choosing a Knight's Armament product is an investment in a legacy of innovation and unwavering quality. For decades, KAC has been at the forefront of firearm technology, developing battle-proven components and complete weapon systems for military, law enforcement, and discerning civilian customers worldwide. Their commitment to research and development, combined with precision manufacturing, has cemented their reputation as a leader in the firearms industry. When you opt for a KAC URX 4, you're not just getting a handguard; you're integrating a piece of professional-grade equipment designed with the same meticulous attention to detail and performance standards as their iconic SR-15 and SR-25 rifles. This trust-building heritage is a significant factor for users seeking the very best for their AR-15.

Is the KAC URX 4 the Right Choice for Your AR-15?

If you're asking, "What is the best handguard for an AR-15 that combines lightweight design, superior stability, and modern modularity?", the KAC URX 4 is a compelling answer. It is ideal for:

• Custom Builders: Those constructing a high-performance AR-15 from the ground up, aiming for a lightweight and highly adaptable platform.
• Performance Upgraders: Owners looking to replace a heavy, outdated, or less stable factory handguard to unlock their rifle's full accuracy potential and enhance accessory mounting options.
• Competitive Shooters: Individuals who benefit from reduced rifle weight for faster transitions and the stable platform necessary for consistent shot placement.
• Tactical Users: Professionals or serious enthusiasts requiring a durable, reliable, and highly configurable forend for duty, defense, or training.

The KAC URX 4 offers a definitive upgrade path, providing the robust foundation needed for a high-performance AR-15. Its thoughtful design, incorporating a full-length Picatinny top rail, M-LOK accessory attachment, and a revolutionary integral barrel nut, ensures that your rifle is not only optimized for precision and customization but also built to last.

Product Specifications

Feature	Detail
Product Line	URX 4 Forend Assembly
Design Type	Free Floating
Overall Length	10.75 Inches
Top Rail	Full Length Picatinny
Accessory Interface	M-LOK
Gas Block Req.	Lo-Profile Gas Block
Mounting System	Integral Barrel Nut
Material	Aluminum
Finish	Hardcoat Anodized
Color	Matte Black
Overall Weight	11.4 Ounces
Inside Diameter	1.55 Inches
Outside Diameter	1.68 Inches
SKU	KM32304-1075
UPC	819064016007