The FN 509 LS Edge is a full-size striker-fired (DAO) pistol in 9mm Luger with a 5-inch barrel and an optic-ready slide. The adapter plate for mounting a red dot is included in the box. 
 

Key Specifications 

• Brand: FN America 
• Model: 509 LS Edge 
• Caliber: 9mm Luger (9x19 PARA) 
• Action Type: Striker-Fired (Double Action Only) 
• Capacity: 17+1 rounds 
• Barrel Length: 5 inches 
• Overall Length: 8.2 inches 
• Weight: 31 oz (approximately 2 lbs) 
• Finish: Graphite PVD Steel with Two-Tone Appearance 
• Sights: Fiber optic front co-witnesses with MRD blackout rear notch 
• Optic Mounting System: Adapter plate included 
   

Features 

The polymer frame has an aggressive grip texture that holds up during sustained fire. The fiber optic front and blackout notch rear give you a clean iron-sight picture and co-witness with a mounted optic. The barrel is steel with a black and graphite PVD coating. The extended slide on the LS Edge gives a longer sight radius than the standard 509 and helps manage recoil on fast follow-up shots. 
 
At 17+1 capacity and 31 oz, this is a full-size carry of range pistol rather than a compact carry gun. The optic-ready design is the main differentiator from a standard 509.

Owners of the FN 509 LS Edge in 9mm consistently point to accuracy and range performance as the gun's strengths. The 5-inch barrel draws specific mention for how it contributes to tighter groups. Ergonomics are well-received — the grip texture and balance suit a range of hand sizes and most shooters find it comfortable through longer sessions.

The optic-ready capability is a genuine draw for those who want to run a red dot without an adapter hack. Build quality is cited as durable and reliable.

On the downside, some shooters find the gun heavy, particularly for all-day carry. Trigger feel is mostly positive but a few owners think the break and reset could be crisper. Price is a recurring discussion point — broadly accepted as fair given the features, though some find it high relative to alternatives. Overall the reception among experienced shooters is strong, and newer owners tend to appreciate the reliability and the optic compatibility.