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$1,800.00
Out of stock
Build Time: 4–6 Weeks | Made in the USA
The SIG MPX is already one of the most innovative pistol caliber platforms ever produced. The Ronin Arms™ MPX-SD K Conversion takes it even further.
Built around our proprietary 5.75″ ported SD barrel and Wakizashi 8″ suppressor, the MPX-SD K transforms standard 115gr and 124gr ammunition into a remarkably soft-shooting, integrally suppressed platform without the need for specialty subsonic ammunition.
The result is a compact SD system that delivers exceptional suppression, reduced recoil, improved accuracy, and outstanding control while maintaining the reliability the MPX platform is known for.
This is not simply a suppressor added to an MPX. It is a complete system engineered to work together.
✔ Ronin Arms™ 5.75″ Ported SD Barrel
✔ Converts standard 115gr and 124gr ammunition to subsonic velocities
✔ Eliminates the need for specialty subsonic ammunition
✔ Optimized for reliable cycling, reduced recoil, and improved accuracy
✔ 18×1 SD mounting interface
✔ Wakizashi Suppressor 8″
✔ Grade 5 Titanium Construction
✔ Precision Laser-Welded Design
✔ Lightweight 9.7 oz Construction
✔ Designed specifically for the MPX-SD K platform
✔ Converts standard 115gr and 124gr ammunition to subsonic velocities
✔ No specialty subsonic ammunition required
✔ Reduced recoil and muzzle movement
✔ Improved accuracy and control
✔ Exceptional sound suppression
✔ Purpose-built specifically for the SIG MPX platform
The MPX-SD K was designed to deliver the benefits of a true SD platform while preserving the compact handling characteristics many shooters prefer.
The MPX-SD K delivers exceptional suppression performance in a compact package.
While the Full Size and K systems offer very similar overall suppression performance, the K system has a slightly different tonal signature due to its shorter overall configuration.
The difference between the two systems is minimal, with most customers choosing based on overall size, balance, and handling preferences rather than sound performance alone.
Compatible with:
✔ SIG MPX Gen 1
✔ SIG MPX Gen 2
✔ SIG MPX Gen 3
❌ Not compatible with monolithic upper receivers, including Copperhead monolithic models.
Please note: Some Gen 1 MPX platforms may require a sealed gas key for proper operation. If your upper requires a replacement gas key, it will be installed during the conversion process and billed separately at $50.
For best performance and reliability:
✔ Use quality brass-cased 115gr or 124gr ammunition
✔ Factory FMJ ammunition is recommended
❌ Do NOT use synthetic-coated, polymer-coated, plated, or coated projectiles
❌ Do NOT use 147gr or heavier ammunition
Using improper ammunition may affect reliability, performance, and warranty coverage.
Midwest Industries 8″ MPX Handguard
✔ Lightweight Design
✔ M-LOK Compatible
✔ Optimized fit for MPX-SD K systems
Some accessories may require shorter mounting screws for proper clearance.
Please send:
✔ Barreled upper receiver only
✔ Printed copy of your order receipt
Additional parts may incur a $50 handling fee and are not guaranteed to be returned.
Please do not send bolts, charging handles, optics, accessories, or additional components unless specifically requested.
Your suppressor will transfer to the FFL/SOT selected during checkout.
After your order is placed, Ronin Arms™ will contact your selected dealer and request the documentation required to complete the transfer.
Transfer timelines are dependent upon how quickly your dealer responds to those requests.
Once your suppressor arrives at your dealer, they will assist you with the ATF Form 4 process.
When your order status changes to Complete, it means your order has been accepted, parts have been allocated, and your project has entered our production schedule.
For conversion services, Complete does not necessarily mean your conversion has shipped.
Tracking information will be provided when your suppressor transfer or completed conversion ships.
The Wakizashi suppressor is designed for an exceptionally long service life and requires minimal maintenance under normal use.
Most customers will never need to clean their suppressor. After approximately 40,000–50,000 rounds, please contact Ronin Arms™ before performing any maintenance. We will be happy to discuss the best cleaning options for your specific suppressor and application.
The suppressor may be cleaned using an ultrasonic cleaner when appropriate.
❌ Do not attempt suppressor disassembly.
Unauthorized modifications void all warranties.
Ronin Arms™ warrants its products against defects in materials and workmanship.
This warranty does not cover misuse, neglect, improper ammunition, normal wear, unauthorized modifications, or damage caused by firing the system without the suppressor installed.
🚨 DO NOT FIRE WITHOUT THE SUPPRESSOR INSTALLED.
Doing so may result in catastrophic damage to the barrel and suppressor system.
✔ Hand tighten only
✔ Do not over-torque
✔ Allow suppressor to cool before removal
✔ Conversion turnaround time is typically 4–6 weeks from receipt of your upper
✔ ATF Form 3 transfer required
✔ ATF approval timelines are outside Ronin Arms™ control
Please note that status inquiries will not accelerate ATF processing times.
All sales are final.
Because every Ronin Arms™ conversion is custom-built to order, cancellations, returns, and refunds are not available once an order has been placed.
NFA items, suppressors, custom builds, and conversion services are non-refundable.
Experience the performance of a purpose-built integrally suppressed system engineered specifically for the SIG MPX platform.
Order your MPX-SD K Conversion today and discover why shooters across the country trust Ronin Arms™ for their SD builds.
| Suppressor Length | 8" |
|---|
Precision USA Manufacturing
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Prompt Communication
Jeffrey L. –
Purchase to range in less than 30 days during the holiday season. Gun runs flawlessly and is “Hollywood” quiet. I am so impressed with this setup I just bought another MPX and will be ordering the full-size setup. A++++ 5 Stars!
Great Job Brother!!!!
Bryan F. –
If you don’t absolutely LOVE it, there is something wrong with you.
Quality work resulting in superior performance. I would not hesitate to do this again, as a matter of fact I’m debating a second one.
Sound suppression is phenomenal, especially when compared to end of barrel suppression. Night and day; don’t want, just get it. You know the saying, buy once cry once.
JT –
Also, I would like to thank you and your team for the incredible work you guys did! After shooting the MPX last weekend for the first time since the modifications, I can confidently say it’s become my favorite gun quite a statement considering my collection.
I truly appreciate all your help throughout the process.
Wishing you a great day ahead!