The FN 509 Midsize Tactical is a striker-fired semi-automatic pistol chambered in 9mm Luger. It has a 4.5-inch threaded barrel (1/2x28), a 10+1 round capacity, and weighs 26.5 oz. The polymer frame comes in Flat Dark Earth, and the package includes 5 magazines and an FN soft case. 
 

Key Specifications 

• Model: FN 509 Midsize Tactical 
• Manufacturer: FN 
• Caliber: 9mm Luger (9x19 Para) 
• Barrel Length: 4.5 inches 
• Overall Length: 7.9 inches 
• Magazine Capacity: 10+1 rounds 
• Weight: 26.5 oz. 
• Frame Material: Polymer 
• Finish: Flat Dark Earth (FDE) 
• Action Type: Striker Fired 
• Magazines Included: 5 
• Sights: Suppressor-height 3-Dot Night Sights 
• Safety Features: Loaded Chamber Indicator 
• Optics Ready: Yes 
• Thread Pattern: 1/2x28 
• Special Features: Threaded Barrel, Fully Ambidextrous Controls, Interchangeable Backstraps 
• Included Case: FN Soft Case 
   

Detailed Features 

The threaded barrel accepts suppressors or muzzle devices directly. Suppressor-height night sights stay visible above most suppressor bodies. The optics mounting system is cut into the slide for direct optic attachment without adapters. Fully ambidextrous controls cover the mag release, slide stop, and frame safety, so the gun works for left- or right-handed shooters out of the box. Three interchangeable backstraps let shooters fit the grip to their hand size.

Owners of the FN 509M Tactical in FDE are generally satisfied with the package, particularly given that it ships with five magazines.

Build quality comes up often in a positive way. The FDE finish holds up well to regular handling and range use. The suppressor-ready setup gets good marks from owners who run cans -- the suppressor-height sights clear most suppressors cleanly, and the threaded barrel is accurate and durable. The optics cut draws consistent praise from buyers who want to mount a red dot.

The ambidextrous controls work as advertised, which left-handed shooters specifically call out as a plus in this price range.

Price is the most common friction point. The 509M Tactical sits toward the high end of the polymer striker-fired market, which some buyers feel is steep even given the features. A smaller number of users mention grip ergonomics as personal preference -- the interchangeable backstraps help, but the grip shape itself isn't for everyone.