When you need a compact duty pistol that balances shootability with concealment-ready dimensions, the right platform has to offer proven controls, reliable ergonomics, and the ability to accept modern optics. We break down the FN 509 MIDSIZE MRD [FDE] *10-ROUND* in detail so you can decide if it fits your defensive and tactical needs.
FN 509 MIDSIZE MRD [FDE] *10-ROUND*
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Design and build: a modern duty pistol in a midsize package
Built as the successor to FN’s FNS line, the FN 509 MIDSIZE MRD [FDE] *10-ROUND* carries forward FN’s reputation for rugged, duty-grade designs while shrinking the footprint for easier carry. The pistol uses a striker-fired system, which delivers a consistent trigger feel that many operators and responsible citizens prefer for defensive work. The polymer frame reduces weight and resists corrosion while still offering a robust platform for daily carry and hard use.
Slide and optics readiness
The MRD series is cut to accept optics using FN’s adapter plates, and the slide comes paired with suppressor-height iron sights designed for proper co-witness with most mini-red dot optics. Optic-ready slides are no longer a luxury — they’re an expectation for modern defensive pistols. Note that optics are not included with this model, so factor that into your accessory list when purchasing.
Ergonomics and concealment
The midsize variant features a 4-inch barrel and a shortened grip, a combination that helps the pistol conceal more easily under a jacket or inside a larger holster. Interchangeable backstraps let you fine-tune grip feel, which improves control and sight tracking for a wide range of hand sizes. Ambidextrous controls mean the pistol is user-friendly for left- and right-handed shooters, including during stress drills and transitions.
Sights, color, and controls
Three-dot style luminescent sights provide a visible sight picture in low-light environments without relying on batteries, and the suppressor-height iron sights allow co-witnessing when an optic is mounted. The FN 509 MIDSIZE MRD [FDE] *10-ROUND* ships in FN’s Flat Dark Earth finish, a durable color scheme that blends into tactical and civilian carry environments without drawing unnecessary attention. This model features no manual safety, emphasizing unencumbered deployment for those who prefer a simpler manual of arms.
Magazine capacity and legal considerations
This package includes two 10-round magazines, making it compliant with jurisdictions that limit magazine capacity while still giving the user a reliable, ready-to-go setup out of the box. At a price of $729.99, the pistol is positioned competitively for a factory optic-ready duty handgun from a major manufacturer. The category is Semi Auto, and the brand is Fn — a name with long-standing credibility in military and law-enforcement circles.
Range performance and handling characteristics
The 4-inch barrel offers a balance of ballistic performance and carryability: you retain most of the velocity and sight radius advantages of a full-size duty pistol while gaining a shorter overall length for concealment. The striker-fired system and well-tuned trigger make follow-up shots predictable, and the polymer frame’s weight savings reduce fatigue during extended training sessions. Whether you’re running slow-fire accuracy drills or rapid defensive strings, the ergonomic options — interchangeable backstraps and ambidextrous controls — help you find a consistent grip that supports repeatable performance.
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Accessories and mounting considerations
If you plan to mount a red dot, the MRD optic cut accepts FN adapter plates; check compatibility with your preferred optic footprint before purchasing an adapter. The suppressor-height sights are an advantage if you intend to run a shielded optic or want backup iron sights that clear taller optic housings. Optics, holsters, and plates will be additional purchases; plan holster selection around whether you will run it with an optic or with iron sights only.
Who this pistol fits
The FN 509 MIDSIZE MRD [FDE] *10-ROUND* is a strong pick for responsible citizens, concealed-carry license holders in restricted-capacity areas, and professionals who want an optic-ready midsize platform from a recognized manufacturer. Its combination of a 4-inch barrel, shortened grip, and two 10-round magazines makes it a pragmatic choice where concealment and legal capacity limits are factors. For those who favor an optic-ready slide and suppressor-height sights, the MRD configuration is particularly attractive.
Training and maintenance notes
Spend time on safety fundamentals and dry-fire practice to build smooth draw and presentation mechanics, especially with a shortened grip. Regular maintenance of the slide, barrel, and recoil system will keep the pistol running reliably. Given that optics are not included, install and zero your chosen red dot at a safe range and verify co-witness with the suppressor-height iron sights if you plan to carry with both.
Purchase and availability
At $729.99, the FN 509 MIDSIZE MRD [FDE] *10-ROUND* is competitively priced for a factory optic-ready pistol from Fn. Clicking the links in this article will take you to the product listing where you can confirm stock, see the “Buy Now” flow, and view accessory options. Check local laws before purchasing and confirm any transfer requirements through your chosen FFL.
Check current availability to see if this configuration is in stock and ready to ship.
The FN 509 MIDSIZE MRD [FDE] *10-ROUND* is a purpose-built midsize striker-fired pistol that brings FN’s duty pedigree into a compact, optic-ready package suitable for concealed carry and professional use. If you value ambidextrous controls, interchangeable backstraps, and the option to run a dot sight with proper co-witnessing, this model deserves a close look.
People Also Ask
What makes this product stand out from competitors?
This product offers superior quality and innovative features that set it apart in the market. Its design focuses on both performance and reliability, making it a top choice for professionals and enthusiasts alike.
Is this product suitable for beginners?
Yes, this product is designed with user-friendly features that make it accessible to beginners while still offering advanced capabilities for experienced users.
What warranty or support is available?
The product comes with comprehensive warranty coverage and excellent customer support to ensure your satisfaction and peace of mind.
How does this compare to similar products in its price range?
This product offers exceptional value for its price point, providing features and quality that typically cost significantly more in comparable alternatives.
What maintenance is required?
Minimal maintenance is required thanks to the product’s durable construction and quality materials. Regular cleaning and occasional inspections will keep it performing optimally.
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