FN 509 MRD Full-Size 9mm FDE, Optics-Ready, 2x17rd
Pros & cons
What works
- Cold hammer-forged barrel rated for 25,000+ rounds — exceeds many competitors' button-rifled barrels
- Includes 4 optic mounting plates — saves $80-120 over aftermarket solutions
- 17-round magazine capacity — 2 rounds more than standard Glock 17 magazines
- MRD system maintains slide integrity — no milling required for optic installation
Trade-offs
- 26.5-ounce weight — 3 ounces heavier than comparable Glock 17 models
- Standard sights not suppressor-ready — requires $90-150 upgrade for co-witnessing
- Flat Dark Earth finish shows holster wear more visibly than black finishes
- Trigger pull measures 5.5-6 pounds — heavier than competition-tuned triggers
Video review
Expert review
Specs at a glance
About this product
The FN 509 MRD Full-Size 9mm FDE is a duty-grade, optics-ready striker-fired pistol engineered for law enforcement and serious civilian applications, featuring a cold hammer-forged barrel and modular MRD system. This firearm represents FN's commitment to meeting military specification standards in a semi-automatic platform available to qualified civilians. The Flat Dark Earth polymer frame provides both durability and distinct contrast for tactical environments.
What is the FN 509 MRD used for?
The FN 509 MRD serves as a duty weapon for law enforcement, home defense platform, and training firearm for competitive shooters requiring optics compatibility. Its 17-round capacity and optics-ready slide make it suitable for extended engagements, while the full-size frame provides stability during rapid fire sequences. The cold hammer-forged barrel ensures consistent accuracy through thousands of rounds without degradation.
How does the FN 509 MRD compare to the Stevens 334 Rifle?
The FN 509 MRD offers faster target acquisition and higher capacity than the bolt-action Stevens 334 Rifle, but lacks the .308 Winchester's long-range ballistics. While the 509 provides 17+1 rounds of 9mm in a semi-auto platform, the Stevens 334 delivers superior accuracy beyond 200 yards with its 20-inch barrel. For home defense and tactical applications under 50 yards, the 509's rapid follow-up shots and red dot compatibility make it the better choice.
What does it weigh and what are the dimensions?
The FN 509 MRD weighs 26.5 ounces unloaded and measures 7.4 inches in length with a 4-inch barrel profile. The slide width measures 1.35 inches, while the overall height with magazine inserted reaches 5.55 inches. These dimensions place it firmly in the full-size service pistol category, providing a stable platform that absorbs recoil effectively.
Who is this NOT for?
This pistol is not suitable for concealed carry due to its full-size dimensions and 7.4-inch overall length. Shooters requiring deep concealment should consider compact alternatives, while those preferring traditional iron sights may find the optics-ready system adds unnecessary complexity. The 26.5-ounce weight also makes it heavier than many comparable polymer-frame pistols by approximately 2-3 ounces.
What's in the box?
The package includes the FN 509 MRD pistol, two 17-round magazines, three interchangeable backstraps, and four optic mounting plates compatible with Trijicon RMR, Leupold DeltaPoint, and similar footprints. Documentation includes warranty information and a basic cleaning kit, with the entire package weighing approximately 3.5 pounds before accessories. The mounting system accommodates optics up to 1.6 inches wide without interference.
Is the FN 509 MRD worth it at $694?
At $694, the FN 509 MRD provides excellent value for shooters requiring military-grade reliability and optics readiness out of the box. The inclusion of multiple mounting plates and magazines represents approximately $150 in additional value compared to competitors requiring separate purchases. For serious defensive use or competition where optic compatibility is mandatory, this pistol justifies its premium over basic models like the Stevens 334 Rifle.
Key attributes
| upc | 845737011697 |
| manufacturer | FN America / FN Herstal |
| manufacturer part number | 66-100722 |
| action | Semi-Auto |
| atf type | Pistol |
| barrel length | 4 |
| caliber/gauge | 9mm |
| capacity | 17 |
| color | Flat Dark Earth |
| length | 11.1000 |
| model | 509 |
| number of magazines | 2 |
| package height | 2.5 |
| package width | 8.3 |
| product type | Semi-Auto Pistol |
| safety | No Manual |
| shipping weight | 3.3 |
| sights | Adjustable Sights |
| sights type | FIXED |
| slide description | Optic Cut/Serrated |
| state restriction (ca) | NO DIRECT SHIP TO CALIFORNIA |
| state restriction (il) | NO SALE TO ILLINOIS PICA |
| state restriction (ri) | NO DIRECT SHIP TO RHODE ISLAND |
| state restriction (wa) | NO DIRECT SHIP TO WASHINGTON |
Frequently asked questions
- Is it compatible with Trijicon RMR optics?
- Yes, the FN 509 MRD includes a specific mounting plate for Trijicon RMR and SRO optics. The plate accommodates the RMR's 1.78-inch footprint without modification. Proper installation requires torqueing the mounting screws to 15 inch-pounds per FN's specifications.
- Does it fit standard holsters?
- The FN 509 MRD fits most holsters designed for the standard FN 509 series. The optics-ready slide adds approximately 0.2 inches of height compared to non-MRD models. Safariland 6005 series holsters require the optics-compatible variant for proper clearance.
- How long does shipping take?
- Ironclad Armory processes FFL transfers within 2 business days after documentation verification. Shipping typically adds 3-5 business days via UPS or FedEx to your selected FFL dealer. All firearms shipments require signature confirmation upon delivery.
- Can I return it if it doesn't fit my hand?
- Firearms cannot be returned once transferred through an FFL due to federal regulations. The three included backstrap sizes accommodate hand sizes from medium to extra-large. We recommend handling the firearm at a local dealer before purchase if fit is a concern.
- Does this work with suppressor-height sights?
- The FN 509 MRD comes with standard-height sights that may not clear most suppressors. Aftermarket suppressor-height sights from Night Fision or Trijicon are required for co-witnessing with optics when using a suppressor. Installation requires a sight pusher tool and approximately 30 minutes of gunsmith time.