RA5-SD K Full Build

Not yet rated


RA5-SD K complete build.

RA5-SD K (MP5-SD style) integral suppressed Semi-Automatic roller-delayed blowback.
Chambered in 9mm.


During checkout, please ensure that you select an FFL (Federal Firearms Licensee) that permits suppressor transfers (SOT). Failure to do so may result in an additional $25 processing fee for us to arrange an eligible FFL on your behalf.
Military and LEO, please contact us to claim your 5% discount.

Discover the Ronin Arms RA5SD-K: Superior Craftsmanship and Performance

The MP5SD-K is a legendary firearm renowned for its reliability, precision, and versatility. At Ronin Arms, we elevate this iconic firearm with our RA5SD-K build, offering enhanced capabilities and integrally suppressed performance. In this comprehensive guide, we’ll delve into the RA5SD-K build’s premium components, meticulous process, and essential considerations that make this firearm a masterpiece.

Why Choose the Ronin Arms RA5SD-K?

The Ronin Arms RA5SD-K is not just another MP5SD-K; it represents the pinnacle of firearm customization. Built with exceptional attention to detail, the RA5SD-K combines the legendary reliability of the MP5SD-K platform with advanced suppression technology and superior craftsmanship. Here are some key reasons why the RA5SD-K stands out:

  • Expert Craftsmanship: Each RA5SD-K build is meticulously crafted by a single, highly skilled gunsmith from start to finish, ensuring consistency and attention to detail.
  • High-Quality Components: Utilizing top-tier materials like LSC receiver flats and precision RCM cold hammer forged barrels, the RA5SD-K is designed for durability and performance.
  • Advanced Suppression: The included DEFCON 4 SD 8″ suppressor offers superior sound suppression, making the RA5SD-K an excellent choice for tactical and stealth applications.
  • Customization Options: With features like an integral 15-slot 1913 rail and various stock options, the RA5SD-K can be tailored to meet specific user preferences.

Components of the RA5SD-K Build

Understanding the components that go into the RA5SD-K build is crucial to appreciating its quality and performance. Here’s a detailed look at each part:

LSC Receiver Flats

The foundation of the RA5SD-K is the LSC receiver flats. These high-quality components are meticulously rolled and welded to create a robust and reliable upper receiver. The precision involved in this process ensures a perfect fit and alignment, critical for the firearm’s overall performance.

Precision RCM Cold Hammer Forged Barrel

At the heart of the RA5SD-K is the RCM cold hammer forged barrel. This barrel is specifically designed for the MP5SD configuration, featuring optimized porting for superior sound suppression. The cold hammer forging process enhances the barrel’s strength and longevity, ensuring consistent performance over time. The RA5SD-K features a 4.75″ barrel, optimized for compactness and maneuverability without sacrificing performance.

DEFCON 4 SD 8″ Suppressor

The DEFCON 4 SD 8″ suppressor included with the RA5SD-K build is a state-of-the-art component that significantly reduces the firearm’s noise signature. While the DEFCON 4 SD 8″ suppressor is compatible with most SD suppressors on the market, including those from B&T, TPM, SilencerCo, and Knights Armament, we suggest using the DEFCON 4 SD 8″ suppressor for optimal performance. This suppressor offers versatility and top-tier performance specifically tuned to enhance the RA5SD-K’s capabilities.

Tungsten Filled Sear-Ready RCM Bolt Group

The tungsten-filled sear-ready RCM bolt group ensures smooth and reliable operation of the RA5SD-K. This high-quality component is essential for the firearm’s semi-automatic roller-delayed blowback operation, providing consistent cycling and enhanced durability.

Anti-Rattle Magazine Release

An anti-rattle magazine release is included to enhance the RA5SD-K’s functionality and ease of use. This feature ensures that the magazine remains securely in place, preventing any unwanted noise or movement during operation.

Rubberized Handguard/Heat Shield

The RA5SD-K features a rubberized handguard and heat shield, providing comfort and protection during extended use. This component helps to dissipate heat and offers a secure grip, enhancing the user’s control over the firearm.

SEF-Type Semi-Auto Trigger Group in HK Grip Module

The SEF-type semi-auto trigger group, housed in an HK grip module, offers precision and reliability. This trigger group is designed for smooth and consistent trigger pull, contributing to the firearm’s overall accuracy and performance.

Integral 15-Slot 1913 Rail

An integral 15-slot 1913 rail is included on the receiver, providing versatility for mounting optics and accessories. Users can opt-out of this feature if preferred, customizing the RA5SD-K to their specific needs.

30-Round Curved Detachable Magazine

Each RA5SD-K build comes with one 30-round curved detachable magazine. This high-capacity magazine ensures that users are ready for extended engagements without the need for frequent reloads.

Professional Coating in HK Black Duracoat

The RA5SD-K is professionally coated in-house in HK Black Duracoat. This durable finish not only enhances the firearm’s appearance but also provides corrosion resistance, ensuring long-lasting protection.

Technical Specifications

Here are the technical specifications of the Ronin Arms RA5SD-K:

  • Caliber: 9mm x 19 Parabellum
  • Barrel Length: 4.75″
  • Barrel Twist: 1:10 with 6 right-hand grooves
  • Operation: Semi-automatic roller-delayed blowback
  • Sights: Rear rotary drum; Front hooded post
  • Stock: B&T side-folding stock (SBR) with other options available upon request

The Build Process

Creating a Ronin Arms RA5SD-K integrally suppressed system is a meticulous process that requires precision and expertise. Here’s a step-by-step guide to the build process:

Installation of the MP5SD-K Ported Barrel

Next, the precision RCM cold hammer forged barrel is installed into the receiver. This barrel is specifically designed for the MP5SD configuration, featuring optimized porting for superior sound suppression. Ronin Arms ensures precise alignment and fitment during this step to guarantee optimal performance.

Fitting of the SD Barrel Shroud and Cocking Tube

The SD barrel shroud and cocking tube are then hand-fitted onto the ported barrel. Ronin Arms makes any necessary adjustments to achieve a secure and precise fit. This step is critical for ensuring the structural integrity and reliability of the RA5SD-K.

TIG Welding

TIG welding is utilized to weld the barrel shroud, cocking tube, and front sight assembly to the receiver. This technique ensures strong, clean welds that are essential for maintaining the firearm’s integrity and performance.

Coating in HK Black Factory Finish

Once the welding is complete, the RA5SD-K is professionally coated in HK Black Duracoat. This durable finish not only enhances the firearm’s appearance but also provides corrosion resistance, ensuring long-lasting protection.

Reassembly and Testing

The RA5SD-K is meticulously assembled, ensuring that all components are properly secured and functioning correctly. Ronin Arms conducts thorough testing, including test firing, to validate the functionality and performance of the completed build.

Quality Assurance

Final inspections and quality checks are performed to verify the integrity of the build. Ronin Arms adheres to strict standards, ensuring that each RA5SD-K meets their high-quality benchmarks and guarantees customer satisfaction.

Important Considerations

While building a Ronin Arms RA5SD-K integrally suppressed system offers numerous benefits, there are some important considerations to keep in mind:

Expertise and Experience

With specialized knowledge and experience in firearm customization, Ronin Arms delivers exceptional craftsmanship and quality in every RA5SD-K build. Their team of skilled gunsmiths ensures that each build meets the highest standards of precision and reliability.

Performance and Reliability

Ronin Arms prioritizes performance and reliability in every RA5SD-K build. By utilizing high-quality components and rigorous testing protocols, they ensure that each firearm operates flawlessly under various conditions. This commitment to excellence makes the RA5SD-K a dependable choice for tactical and stealth applications.

Cost and Investment

Building an RA5SD-K with Ronin Arms is a worthwhile investment. The superior craftsmanship, performance enhancements, and added value to the firearm justify the cost. Additionally, the RA5SD-K’s durability and reliability ensure long-term satisfaction for owners.

Parts Availability

The availability of specific parts required for the RA5SD-K build can impact the overall timeline. Ronin Arms effectively manages this aspect by sourcing high-quality components from trusted suppliers. Their dedication to maintaining the integrity and performance of the firearm ensures that each build meets the highest standards.

RA5SD-K in Action

The RA5SD-K is designed for a variety of applications, making it a versatile addition to any firearm collection. Here are some scenarios where the RA5SD-K excels:

Tactical Operations

The integrally suppressed RA5SD-K is ideal for tactical operations where stealth and precision are paramount. Its advanced suppression technology reduces noise, allowing operators to maintain a low profile during missions.

Home Defense

For home defense, the RA5SD-K offers reliable performance and ease of use. Its compact size and integrally suppressed barrel make it an excellent choice for close-quarters engagements, providing peace of mind and security.

Law Enforcement

Law enforcement agencies can benefit from the RA5SD-K’s superior sound suppression and reliable operation. The firearm’s high-quality components and meticulous build process ensure consistent performance in critical situations.

Recreational Shooting

Shooting enthusiasts will appreciate the RA5SD-K’s precision and craftsmanship. Whether for target practice or competitive shooting, the RA5SD-K offers an enjoyable and rewarding experience.

Customization Options

Ronin Arms offers a range of customization options for the RA5SD-K, allowing users to tailor the firearm to their specific needs. Here are some of the available options:

Opt-Out of Integral 15-Slot 1913 Rail

Users can choose to opt-out of the integral 15-slot 1913 rail if they prefer a different mounting solution. This customization option allows for greater flexibility in configuring the firearm.

Stock Options

The RA5SD-K comes standard with a B&T side-folding stock, but other stock options are available upon request. This allows users to choose the stock that best fits their ergonomic and tactical preferences.

Additional Accessories

Ronin Arms offers a variety of accessories to enhance the RA5SD-K’s functionality and performance. From optics and sights to tactical lights and lasers, users can fully customize their firearm to meet their specific requirements.

Purchasing and FFL Requirements

Selecting an FFL

When purchasing the RA5SD-K, it is crucial to select an FFL (Federal Firearms Licensee) that permits suppressor transfers (SOT). This ensures a smooth and legal transaction. During checkout, please ensure that you choose an eligible FFL to avoid any delays or additional fees.

Warranty Coverage

Ronin Arms LLC guarantees that the RA5SD-K integrally suppressed 9mm is free from defects in workmanship and materials. This warranty covers repair or replacement at our discretion for this suppressor. However, it is important to note the following:

  • Non-Serviceable Suppressor: The suppressor included with your RA9SD-K is non-serviceable. Do not attempt to disassemble or modify it.
  • No Warranty for Merchantability: There is no warranty for the merchantability or fitness of this suppressor for specific purposes.

Return Policy

If you encounter any issues with your suppressor, contact us before attempting any returns. Shipping a suppressor without prior approval may result in legal complications. Follow these steps for returns:

  1. Contact us at info@roninarmsaz.com with details of your issue.
  2. Wait for our review and instructions before shipping any items.

Installation and Removal Instructions

Safety First

Before installing or removing the suppressor, ensure the firearm is unloaded and the safety is engaged. Follow these steps to avoid accidents:

  1. Unload the Firearm: Remove the magazine and verify that the chamber is empty.
  2. Engage the Safety: Ensure the firearm’s safety is engaged to prevent accidental discharge.

Installation Procedure

  1. Inspect the Threads: Verify that the muzzle threads and caliber correspond to the suppressor specifications.
  2. Thread the Suppressor: Carefully thread the suppressor onto the barrel’s rear threads. Hand tighten—do not over-tighten.
  3. Check Alignment: From the rear of the firearm, visually inspect the fitment of the suppressor to ensure it does not obstruct the bore. Never inspect bore alignment from the front of the firearm.

Removal Procedure

  1. Cool Down: Allow the suppressor to cool to room temperature before attempting removal.
  2. Unscrew by Hand: Gently unscrew the suppressor by hand. Use tools only if necessary and with caution to avoid damaging the threads.

Important Safety Information

Handling Precautions

  • Loaded Firearm: Never install or remove the suppressor from a loaded firearm.
  • Bore Inspection: Always inspect the bore alignment from the rear, never from the front, to avoid accidents.
  • Extreme Caution: Handle firearms and suppressors with extreme caution to prevent severe injury or death.

Legal Compliance

Ensure all actions comply with federal, state, and local laws. Misuse or improper handling of suppressors can lead to serious legal consequences.


The Ronin Arms RA5SD-K is the pinnacle of MP5SD-K builds, combining exceptional craftsmanship, high-quality components, and advanced suppression technology. From the meticulous build process to the final quality assurance checks, every aspect of the RA5SD-K is designed to deliver superior performance and reliability.

Whether for tactical operations, home defense, law enforcement, or recreational shooting, the RA5SD-K is a versatile and dependable choice. With customization options and a commitment to excellence, Ronin Arms ensures that each RA5SD-K build exceeds expectations.

Contact Ronin Arms today to start your custom build journey and elevate your arsenal with the unparalleled RA5SD-K. For more information, visit our website or reach out to us directly via email or phone. Let Ronin Arms take your MP5 to the next level.

Frequently Asked Questions (FAQs)

What is the build time for the RA5SD-K?

The current build time for a full RA5SD build is approximately 8-10 weeks, depending on parts availability. Ronin Arms strives to deliver builds within this time frame while maintaining the highest quality standards.

Can I customize my RA5SD build?

Yes, Ronin Arms offers various customization options for the RA5SD. Customers can opt-out of the integral 15-slot 1913 rail, choose different stock options, and add additional accessories to tailor the firearm to their specific needs.

Is the RA5SD compatible with other suppressors?

The DEFCON 4 SD 12″ suppressor included with the RA5SD-K build is compatible with most SD-K suppressors on the market, including those from B&T, TPM, SilencerCo, and Knights Armament. However, we suggest using the DEFCON 4 SD 12″ suppressor for optimal performance, as it is specifically tuned to enhance the RA5SD’s capabilities.

What type of warranty does Ronin Arms offer for the RA5SD?

Ronin Arms stands behind the quality and craftsmanship of their RA5SD-K builds. They offer a warranty that covers any defects in materials or workmanship, ensuring that customers can purchase with confidence.

How can I order a custom RA5SD-K build?

To order a custom RA5SD-K build, visit the Ronin Arms website or contact them directly via email or phone. Their team will guide you through the process, discuss customization options, and provide a timeline for the build.

The Ronin Arms RA5SD-K represents the ultimate in MP5SD-K builds, offering unparalleled performance, reliability, and customization. Whether you’re a tactical operator, law enforcement professional, or shooting enthusiast, the RA5SD-K is designed to meet and exceed your expectations. Trust Ronin Arms to deliver a firearm that stands out in both quality and performance.


Barrel Length


Barrel Twist

1:10 with 6 right-hand grooves

Suppressor Length



There are no reviews yet.

Be the first to review “RA5-SD K Full Build”
Welcome to Ronin Arms, in order to browse our site you must be at least 18 years of age.
Are you at least 18 years old?
Your Cart