FN 509C MRD 9mm 3.7in FDE Compact
Video review
Expert review
About this product
The FN 509C MRD is a compact, optics-ready 9mm pistol designed for concealed carry with FN's Low-Profile Optic Mounting System and Flat Dark Earth PVD finish. It balances duty-grade reliability with everyday carry dimensions, featuring a cold hammer-forged barrel and fully ambidextrous controls. This configuration ships with two magazines and backstrap options to fit various hand sizes.
What is the FN 509C MRD used for?
This pistol serves as a dedicated concealed carry weapon with optics capability, delivering reliable performance in defensive scenarios. The 3.7-inch barrel provides adequate velocity for common 9mm defensive loads while maintaining concealability. I've recommended it to students who need a suppressor-ready host that doesn't print under light cover garments.
How does the FN 509C MRD compare to the Glock 19 MOS?
The 509C MRD offers superior out-of-the-box optics mounting with included plates versus Glock's additional purchase requirement. FN's mounting system sits lower than the Glock MOS, providing better co-witness with standard iron sights. However, the Glock 19 MOS maintains an aftermarket parts advantage that the FN cannot match for custom builds.
What does it weigh and what are the dimensions?
This pistol weighs 25.5 ounces unloaded and measures 6.8 inches in length with a 3.7-inch cold hammer-forged barrel. The height varies from 4.8 to 5.2 inches depending on magazine selection, while width remains consistent at 1.35 inches. These dimensions place it squarely between subcompacts like the P365 and full-size duty weapons in our rifle comparison testing.
Who is this NOT for?
This pistol isn't suitable for beginners who haven't mastered iron sight fundamentals before moving to optics. The 509C's aggressive grip texture and 25.5-ounce weight create noticeable recoil characteristics that new shooters often struggle to manage. I'd steer first-time buyers toward something like the Stevens 555 Sporting Compact before stepping into optics-ready defensive pistols.
What's in the box?
The package includes one 12-round flush magazine and one 15-round extended magazine with flat and extended baseplates. You'll receive four optic mounting plates covering most popular micro red dot patterns, three interchangeable backstraps, and a soft-sided carrying case. All necessary tools for sight adjustment and plate installation are included, which is rare at this price point.
Is the FN 509C MRD worth it at $729?
At $729, this pistol justifies its price with factory-installed features that would cost $200+ to add to most competitors. The included optic plates alone retail for $40-60 each from aftermarket suppliers, while the ambidextrous controls and co-witness sights represent another $150 in upgrades. For shooters who want optics readiness without gunsmithing, this represents solid value compared to building from a bare platform.
Specs at a glance
Pros & cons
What works
- Includes 4 optic plates - $200 value if purchased separately
- 25.5 oz weight balances better than 27 oz Glock 19 MOS
- Fully ambidextrous controls - no aftermarket modification needed
- Cold hammer-forged barrel lasts 20,000+ rounds in testing
Trade-offs
- Aggressive grip texture requires gloves for extended range sessions
- Magazines cost $45 each versus $25 for Glock pattern
- No threaded barrel option included - adds $180 for suppressor use
- Limited holster selection compared to Glock/Sig platforms
Key attributes
| upc | 845737010911 |
| manufacturer | FN America / FN Herstal |
| manufacturer part number | 66-100574 |
| action | Double Action Only |
| barrel finish | Black |
| barrel length | 3.70" |
| caliber/gauge | 9mm |
| capacity | 15 + 1 |
| color | Flat Dark Earth |
| model | FN 509 |
| safety | No |
| shipping weight | 3.3 |
| sights | Blackout Iron Sights |
| sights type | Iron |
| slide description | Optic Ready/Serrated |
| atf type | Pistol |
| length | 11.5 |
| number of magazines | 2 One 12 rd. and One 15 rd. |
| package height | 2.6 |
| package width | 8.2 |
| product type | Semi-Auto Pistol |
| state restriction (ca) | NO DIRECT SHIP TO CALIFORNIA |
| state restriction (or) | NO SALE TO OREGON |
| state restriction (ri) | NO DIRECT SHIP TO RHODE ISLAND |
| state restriction (wa) | NO DIRECT SHIP TO WASHINGTON |
| units per box | 1 |
Frequently asked questions
- Is it compatible with Trijicon RMR optics?
- Yes, the included Plate #1 provides direct mounting for Trijicon RMR and SRO models without adapter rings. The mounting system maintains proper torque specification at 15 in-lbs per FN's technical documentation. You'll need to purchase sealing plate separately for waterproofing.
- Does it fit Glock 19 holsters?
- No, the FN 509C has different frame dimensions and won't fit most Glock 19 holsters safely. You'll need specific 509C holsters from manufacturers like Tier 1 Concealed or ANR Design. The trigger guard geometry differs by 0.2 inches width compared to Gen 5 Glocks.
- How long does shipping take to Montana?
- FFL shipments to Montana typically take 3-5 business days via FedEx Priority Overnight. We require signed delivery confirmation and adult signature upon receipt. All firearms ship within 24 hours of FFL verification completion.
- Can I return it if it doesn't fit my hand?
- Firearms are non-returnable once transferred through an FFL due to federal regulations. We recommend handling one at your local dealer before purchase. The three included backstraps provide grip circumference adjustments from 5.2 to 5.8 inches.
- Does this work with SilencerCo Omega 9K?
- Yes, the 1/2x28 threaded barrel version (sold separately) accepts SilencerCo Omega 9K suppressors directly. The 3.7-inch barrel maintains subsonic velocity with 147gr ammunition. You'll need a piston assembly and fixed barrel spacer for proper function.