The FN 509 Tactical is a full-size 9mm pistol built by FN America. It runs double action only and comes with two magazines: one 17+1 and one 24+1. The 4.5-inch cold hammer-forged barrel is threaded 1/2"x28 for suppressors or muzzle devices. Suppressor-height Trijicon 3-dot green tritium night sights are factory-installed and co-witness with common red dot optics. Weight is 27.9 oz with the polymer frame and matte black stainless steel slide. 
 

Key Specifications 

• Brand: FN America 
• Model Name: 509 Tactical 
• Caliber: 9mm Luger 
• Action: Double Action Only (DAO) 
• Capacity: 17+1 / 24+1 (includes two magazines) 
• Barrel Length: 4.5 inches 
• Overall Length: 7.9 inches 
• Weight: 27.9 oz 
• Frame Material: Polymer with Picatinny Rail 
• Slide Material: Stainless Steel with Matte Black Finish 
• Sights: Suppressor Height Trijicon 3-Dot Green Tritium Night Sights 
   

Detailed Features 

The optic-ready slide accepts direct-mount red dots that co-witness with the suppressor-height night sights. Interchangeable textured backstraps let you tune the grip to your hand size. A loaded chamber indicator gives a visual confirmation without needing to cycle the slide. The integrated Picatinny rail runs accessories like lights and lasers directly without an adapter.

The FN 509 Tactical gets solid marks in most discussions, with a few areas that generate consistent criticism.

Accuracy out of the box is a frequent talking point. The quality manufacturing and 4.5-inch barrel produce tight groups, and users generally report that it shoots well without needing immediate upgrades.

The grip design is well regarded. The interchangeable backstraps let you dial in the fit, and most users find it comfortable for extended range sessions without fatigue.

The threaded barrel and suppressor-height night sights are practical inclusions. Owners with suppressors or muzzle devices appreciate having the hardware already spec'd for it from the factory.

Factory night sights get consistent positive feedback for low-light performance, which is relevant for anyone considering it for home defense.

Reliability across ammunition types is generally reported as good, which builds confidence for defensive use.

On the critical side: the gun is on the heavier end at 27.9 oz, which matters for carry. The trigger pull gets mixed reviews -- some users find it heavier than they prefer, and a few note it's not as smooth as competing options. Aftermarket support is thinner compared to more common pistol platforms, which limits accessory options. Pricing compared to competitors comes up regularly as a consideration.