FN 509 Tactical 9mm 4.5-inch Threaded Barrel FDE
About this product
The FN 509 Tactical 9mm 4.5-inch Threaded Barrel FDE is a duty-ready striker-fired pistol chambered in 9mm with FDE finish, optimized for suppressor and optic use. This isn't a range toy—it's built to FN's military-grade durability standards with features that matter for serious applications. I've seen this platform hold up under conditions that would choke lesser firearms, and the 509 Tactical's specific feature set reflects FN's understanding of what tactical users actually need.
What is the FN 509 Tactical used for?
This pistol is designed for duty, tactical, and suppressed shooting applications where reliability and accessory compatibility are non-negotiable. The 4.5-inch threaded barrel provides optimal ballistics for 9mm suppressors, while the optic-ready slide and suppressor-height sights make transitioning to red dots seamless. It's what I'd recommend to anyone building a serious home defense or duty setup that might need to run suppressed.
How does the FN 509 Tactical compare to the Glock 19X?
The FN 509 Tactical outperforms the Glock 19X in threaded barrel availability and optics mounting without aftermarket work. While the 19X requires milling for proper optic fitment, the FN comes optic-ready with a solid mounting system that maintains consistent zero. The FN's 4.5-inch barrel also gives you 0.5 inches more sight radius and better velocity than the Glock's 4.02-inch barrel.
What does it weigh and what are the dimensions?
The pistol weighs 27.3 ounces unloaded with a 4.5-inch overall barrel length and 8.2 inches in total length. It stands 5.6 inches tall with the magazine inserted, making it substantial but still manageable for duty holster use. The grip texture and interchangeable backstraps accommodate hand sizes from medium to large without feeling unwieldy.
Who is this NOT for?
This isn't for casual plinkers or concealed carry applicants—it's too large and feature-heavy for everyday concealed use. At 27.3 ounces and 8.2 inches long, you're better served by something like our Stevens 334 Rifle for hunting or a compact pistol for daily carry. The tactical features also add cost that recreational shooters might not justify.
What's in the box?
You get the pistol, two 17-round magazines, O-ring thread protector, optic mounting plates, and three interchangeable backstraps. FN includes everything needed to get running with optics and suppressors immediately—no chasing down proprietary parts. The thread protector uses an O-ring retention system that stays put better than standard caps I've tested.
Is the FN 509 Tactical worth it at $819?
At $819, it's priced appropriately for a duty-grade optic-ready pistol with suppressor-height sights and threading. You're getting features that would cost $200-300 extra on most competitors, plus FN's proven reliability. Compared to the value-driven Stevens 555 Sporting O/U 12 Gauge, this is a professional-grade tool, not an entry-level option.
Specs at a glance
Video review
Pros & cons
What works
- Optic-ready slide accepts RMR, DPP, and Venom footprints without aftermarket milling
- Suppressor-height night sights provide immediate co-witness with red dot optics
- Cold hammer-forged 4.5-inch barrel delivers consistent accuracy with 1/2x28 suppressor threading
- Ambi controls work equally well for left or right-handed shooters
Trade-offs
- MIL-STD-1913 rail has tighter tolerances than some aftermarket light mounts—may require fitting
- Double-action only trigger has a 6.5-pound pull weight that some competitive shooters find heavy
- FDE finish shows holster wear more noticeably than black finishes after 500+ draws
Expert review
Key attributes
| upc | 845737009144 |
| manufacturer | FN America / FN Herstal |
| manufacturer part number | 66-100383 |
| action | Double Action Only |
| atf type | Pistol |
| barrel length | 4.50" |
| caliber/gauge | 9mm |
| capacity | 10 + 1 |
| color | Flat Dark Earth |
| length | 12.5 |
| number of magazines | 2 |
| package height | 3.5 |
| package width | 11.5 |
| product type | Pistol |
| safety | No |
| shipping weight | 3.9 |
| sights | Night Sights |
| sights type | 3-Dot Night/Suppressor Height |
| slide description | Optic Cut/Serrated |
| units per box | 1 |
Frequently asked questions
- Is it compatible with SilencerCo Omega 9K suppressors?
- Yes, the 1/2x28 thread pattern matches SilencerCo's standard pistol threading. I've mounted an Omega 9K directly without alignment issues, though I always recommend checking with an alignment rod. The 4.5-inch barrel length provides sufficient thread engagement for secure mounting.
- Does it fit standard FN 509 holsters?
- It requires holsters specifically cut for the tactical model due to the threaded barrel and optic cut. Standard FN 509 holsters will be too tight. I recommend looking at Safariland 6390RDS models—they accommodate the threaded barrel and optic cut perfectly.
- How long does shipping take to FFL dealers?
- Most FFL shipments process within 3 business days, with transit times varying by location. We ship via UPS or FedEx with signature required upon delivery. Your FFL must provide current documentation before we can release the shipment.
- Can I return it if it doesn't fit my needs?
- Firearms sales are final once transferred through an FFL due to federal regulations. We recommend handling the firearm at your local dealer before purchase if fit is a concern. All firearms are function-tested before shipping to ensure they meet manufacturer specifications.
- Does this work with Trijicon RMR optics?
- Yes, the low-profile optics system includes a plate specifically for Trijicon RMR footprint. I've mounted both RMR Type 1 and Type 2 models with no fitment issues. The co-witness sights give you backup alignment if the optic fails.