The FN 509 Midsize Tactical is a semi-automatic pistol built for tactical use and range work alike. Striker-fired and optics-ready from the factory, it handles both competitive shooting and personal defense without needing significant modification out of the box. 
 

Key Specifications 

• Manufacturer: FN 
• Family: 509 Series 
• Model: FN 509 Midsize Tactical 
• Type: Semi-Auto Pistol 
• Action: Striker Fired 
• Caliber/Gauge: 9mm 
• Finish: Black Polymer Frame 
• Barrel Length: 4.5" 
• Overall Length: 7.9" 
• Capacity: 10 + 1 rounds (includes two magazines) 
• Sights: Holosun 407C (optics-ready) 
• Thread Pattern: 1/2x28 
• Special Feature: Threaded Barrel for suppressor compatibility 
   

Detailed Features 

The optics-ready cut accepts red dot sights directly, so there's no adapter plate to fiddle with. The 4.5" threaded barrel accepts suppressors and compensators via the 1/2x28 thread pattern. Holosun 407C sights come mounted from the factory and hold zero well in low light. Controls are fully ambidextrous (magazine release, slide stop, and safety all work without shifting your grip), and three interchangeable backstraps let you dial in the grip size.

The FN 509 Tactical gets consistently positive marks in community discussions. Accuracy at longer distances comes up often. Shooters find it punches above its price class for precision, which makes it a regular pick for both USPSA-style competition and defensive carry.

The optics-ready design draws a lot of attention. Being able to drop a red dot directly onto the frame without an adapter plate is a practical advantage that shooters notice quickly at the range. The threaded barrel gets similar praise from owners who run suppressors.

Ergonomics land well for most people. The grip texture gives a secure purchase without being abrasive, and the ambidextrous controls mean left-handed shooters aren't penalized. Build quality reads as solid: the pistol doesn't feel plasticky despite the polymer frame, and durability holds up through high round counts.

Price occasionally comes up as a sticking point. At its typical street price it sits above several competitors, so buyers do the math against comparable guns before pulling the trigger. Most conclude the feature set justifies the cost, but it's a real consideration.