The FN 509 Tactical is a 9mm semi-automatic pistol in Flat Dark Earth finish, with a 4.5-inch threaded barrel, optic-cut slide, and suppressor-height night sights. The FDE finish covers both the polymer frame and stainless steel slide. 
 

Key Specifications 

• Brand: FN 
• Model: FN 509 Tactical 
• Caliber: 9mm Luger 
• Action: Double Action Only (DAO) 
• Capacity: 10+1 rounds 
• Barrel Length: 4.5 inches (threaded) 
• Overall Length: 7.9 inches 
• Weight: 27.90 oz 
• Frame Material: Polymer with Flat Dark Earth finish 
• Slide Material: Stainless Steel with Flat Dark Earth finish and optic cut 
• Sights: Suppressor Height 3-Dot Night Sights 
• Grip Type: Standard with interchangeable backstraps 
   

Detailed Features 

The threaded barrel attaches suppressors or muzzle devices directly. The optic-cut slide accepts a range of red dot footprints. Suppressor-height night sights clear the top of a suppressor body, so you retain a usable sight picture when suppressed. 
 
Interchangeable backstraps let shooters adjust grip circumference. The textured polymer frame provides traction without being aggressive on the hand during longer sessions. 
 

Usage Scenarios 

• Home Defense: Suppressor-ready and night-sight equipped for low-light use. 
• Competitive Shooting: Optic cut and adaptable grip suit action shooting formats. 
• Tactical Training: The threaded barrel and accessory rail accommodate lights, lasers, and suppressors.

The FN 509 Tactical 9mm in FDE with threaded barrel and night sights is generally well-received, with owners pointing to build quality and practical features as its main strengths.

Build quality and reliability are the most consistent positives. Users describe a solid, well-fitted pistol that functions reliably across various conditions and ammunition types. The FDE finish is noted as attractive and uniform across frame and slide.

Ergonomics get favorable comments. The grip fills the hand well, and the interchangeable backstraps help shooters dial in fit. The pistol remains comfortable through extended range sessions.

Accuracy is regularly praised. Most owners report tight, consistent groups with quality 9mm loads.

The threaded barrel is valued by owners who want suppressor capability without modification. Night sights are highlighted as a practical factory inclusion for defensive use.

Weight is the most common drawback. At 27.90 oz, some buyers find it heavy compared to competing compact or duty 9mm options, particularly for everyday carry.

Trigger feel is mixed. Some find it acceptable; others prefer the crisper pull or shorter reset of competing platforms. It is functional, but not a standout feature.

Accessory compatibility comes up as a minor concern -- holsters and some aftermarket parts for this specific model can be harder to find than for Glock or SIG platforms.

Price draws occasional criticism from buyers who feel the FN 509 Tactical sits above comparable duty pistols in cost.