Description
The FN 509M Midsize Tactical 9mm 4.5″ Threaded – 5x10rd is a factory-built multi-role handgun that bridges the gap between compact carry and full-size duty performance. With a 4.5-inch threaded barrel, optics-ready slide, and suppressor-height night sights, this pistol is ready for suppressed shooting or red-dot mounting right out of the box. It ships with five 10-round magazines for extended training sessions and range days.
| Manufacturer | FN America (per manufacturer specs) |
|---|---|
| Model | FN 509M Midsize Tactical |
| Caliber | 9mm |
| Barrel Length | 4.5 inches (threaded, 1/2×28) |
| Capacity | 5×10 rounds |
| Overall Length | 7.6 inches |
| Weight | 27.3 ounces (unloaded, per FN specs) |
| Slide Material | Stainless steel with black nitride finish |
| Frame Material | Polymer with enhanced texture |
| Safety | Trigger safety, passive striker block |
| Condition | New |
Key Features
- Factory-Threaded Barrel – The 4.5-inch, 1/2×28 threaded barrel lets you attach a suppressor without aftermarket work. This matters for shooters who want quiet range sessions or reduced muzzle rise with a compensator.
- Optics-Ready Slide – The slide is pre-milled for popular red-dot footprints. This matters because you can mount a reflex sight without sending the slide to a machine shop.
- Suppressor-Height Night Sights – Tall three-dot night sights co-witness through most red-dot optics. This matters for low-light shooting and backup aiming if the dot fails.
- Five 10-Round Magazines – This package includes five magazines, which matters for high-volume training, competition practice, or keeping spares in a range bag.
- Ambidextrous Controls – The slide stop and magazine release are fully ambidextrous. This matters for left-handed shooters or those who train with support-hand manipulations.
Who It’s For
This pistol is for the southern shooter who wants one gun for both the dove field and the nightstand. It suits the hunter who runs suppressed on a deer stand, the concealed carrier who prefers a midsize frame, and the tactical shooter who trains with a red dot. The 4.5-inch barrel gives you a longer sight radius than a compact, but the grip is shorter than a full-size for easier concealment.
Pros & Cons
- Pro: Factory optics cut saves you $100–200 in milling costs. Con: The 10-round magazine limit may be restrictive for shooters in free states who prefer standard-capacity mags.
- Pro: Threaded barrel is standard, not an add-on. Con: The included thread protector can loosen under recoil unless you use thread-locker.
- Pro: Five magazines is generous for the price point. Con: The aggressive texture on the grip can wear on bare skin during all-day carry.
How It Compares
| Feature | FN 509M Midsize Tactical | Zev Technologies OZ9 | Agency Arms AOS |
|---|---|---|---|
| Barrel Length | 4.5″ threaded | 4.5″ threaded (optional) | 4.5″ threaded (optional) |
| Optics Ready | Yes, factory | Yes, factory | Yes, via AOS plate |
| Magazines Included | 5 | 2 | 2 |
| MSRP | $798.66 | $1,299+ | $1,199+ |
| Trigger Pull (approx.) | 5.5–6.5 lbs | 4.5–5.5 lbs | 4.5–5.5 lbs |
| Ambidextrous Controls | Full ambi | Partial | Partial |
FAQ
Does the FN 509M Midsize Tactical come with a suppressor?
No. The pistol includes a threaded barrel and thread protector, but a suppressor is not included. It is compatible with most 1/2×28 threaded 9mm suppressors.
What red-dot optics fit the factory slide cut?
The slide is cut for the Trijicon RMR footprint, which also accepts Holosun 407C/507C/508T, Vortex Viper/Venom, and other RMR-pattern optics. Adapter plates are available for other footprints.
Can I carry this pistol concealed?
Yes. The 4.5-inch barrel and 7.6-inch overall length make it a midsize—slightly larger than a compact but more concealable than a full-size. A quality holster with a claw works well for IWB carry.
Are the magazines interchangeable with other FN 509 models?
Yes. These 10-round magazines fit all FN 509 series pistols (compact, midsize, and full-size). Standard-capacity 17- and 24-round magazines also work in this gun.
What is the warranty on this pistol?
FN America provides a limited lifetime warranty to the original owner. Per FN specs, coverage applies to defects in materials and workmanship.
Why Buy From Us
- ✅ Nationwide delivery (all 50 states)
- ✅ Ships 1–2 business days
- ✅ 30-day returns
- ✅ Secure checkout
Browse more in our Semi Auto Handguns or check out FN Handguns and Tactical Pistols.
Last updated: April 2026
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