The FN 509 Tactical is a striker-fired 9mm pistol with a 4.5-inch threaded barrel, suppressor-height night sights, and a low-profile optics mounting system. It weighs 27.90 oz (1.74 lbs) and holds 10+1 rounds. The polymer frame is matte black, the slide is stainless steel. 
 

Key Specifications 

• Brand: FN America 
• Model: 509 Tactical 
• Caliber: 9mm Luger (9x19 PARA) 
• Action: Semi-Auto Striker Fired 
• Capacity: 10+1 rounds 
• Barrel Length: 4.5 inches (threaded) 
• Weight: 27.90 oz (1.74 lbs) 
• Finish: Matte Black 
• Frame Material: Polymer 
• Slide Material: Stainless Steel 
   

Detailed Features 

The threaded barrel accepts suppressors and muzzle devices directly without an adapter. Suppressor-height fixed three-dot night sights remain visible above most cans. The low-profile optics mounting system is a direct-mount setup -- no adapter plate needed for compatible red dots. 
 
Interchangeable backstraps in three sizes let you fit the grip to your hand. The textured grip surface is aggressive enough to hold securely without being abrasive through a holster. FN's striker-fired trigger has a consistent pull with a short, positive reset. 
 

Usage 

The 509 Tactical is purpose-built for suppressor use, which explains the combination of threaded barrel, suppressor-height sights, and direct-mount optics system. Law enforcement agencies have adopted it as a duty pistol. For civilian use it works well as a range pistol or home defense gun, especially for anyone running a suppressor. The 10+1 standard capacity can be extended with higher-capacity magazines.

The 509 Tactical gets consistent marks for build quality and reliability -- FN's manufacturing reputation carries over to this platform, and owners report few issues across high round counts.

The optics-ready setup draws regular praise. The direct-mount system is clean and eliminates the play sometimes found in adapter-based solutions. Shooters who run the gun with a red dot find the sight picture intuitive, and the suppressor-height irons co-witness adequately.

The trigger feedback is split. Some shooters find the pull crisp and the reset short; others compare it unfavorably to tuned triggers on competing platforms and feel there's room for improvement stock. Aftermarket trigger options exist for those who want to address this.

Price is the consistent friction point. The 509 Tactical is priced above many competitors, and some buyers question whether the suppressor-specific features are worth the premium if they don't plan to run a can. FN's customer service gets mixed reviews -- mostly positive, but with some reports of slower response times.

Aftermarket support -- holsters, optics plates, accessories -- is solid given the platform's law enforcement adoption.