The FN 509 Midsize Tactical is a striker-fired 9mm pistol with a 4.5" threaded barrel, no manual safety, and suppressor-height 3-dot night sights. It ships with two magazines: one 15+1 and one 24+1. At 1.7 lbs. and 7.9" overall it sits in the midsize frame category, balancing carry practicality with a full grip. 
 

Key Specifications 

• Brand: FN America 
• Model Name: 509 Midsize Tactical 
• Caliber: 9mm Luger (9x19 Para) 
• Action Type: Striker Fired 
• Capacity: 15+1 / 24+1 (2 magazines included) 
• Barrel Length: 4.5 inches (threaded, 1/2 x 28) 
• Overall Length: 7.9 inches 
• Weight: 1.7 lbs 
• Sights: Suppressor-height 3-dot night sights 
• Grip: Black textured with interchangeable backstraps 
• Safety Style: No manual safety 
• Finish Color: Matte Black 
   
  The FN Low Profile Optics Mounting System accepts multiple red dot footprints with the same slide cut. The threaded barrel ships with a thread cap and is 1/2 x 28 for standard suppressors and compensators. Suppressor-height sights co-witness above a mounted can. The Duty-Safe trigger has a pull weight of approximately 5.6 lbs. The modular backstrap system has three sizes for grip fit. The frame includes a Picatinny rail for weapon lights.

The FN 509 Midsize Tactical gets consistently strong reviews for build quality and suppressor-ready features. The threaded barrel and suppressor-height sights as factory equipment draw specific appreciation from shooters who use cans - it removes the need for aftermarket parts before the pistol is usable suppressed. The optics mounting system is praised for its flexibility across different red dot footprints.

Ergonomics are generally well-received: the grip texture is secure without being abrasive, and the interchangeable backstraps accommodate different hand sizes. The Duty-Safe trigger is described as consistent and predictable.

The midsize frame is occasionally noted as on the larger side for concealed carry compared to more compact options, which is an honest tradeoff for the 15+1 capacity and suppressor features. Pricing and aftermarket accessory availability relative to Glock-pattern pistols come up in comparisons. Overall sentiment is positive, particularly among shooters specifically interested in the suppressor and optics-ready feature set.