The FN 509MT is a striker-fired 9mm pistol with a 4.5-inch barrel and 15+1 capacity. It ships in Flat Dark Earth with 3-dot suppressor-height night sights and an interchangeable FDE backstrap for grip sizing. 
 

Key Specifications 

• SKU: 2024014372 
• UPC: 845737018429 
• Brand: FN 
• Model Name: 509MT 
• MPN: 66101938 
• Caliber: 9MM LUGER 
• Action: Striker Fire 
• Capacity: 15+1 RD 
• Barrel Length: 4.5" 
• Overall Length: 12" 
• Sights: 3-Dot Night/Suppressor Height 
• Grip: FDE Interchangeable Backstrap 
• Trigger Type: Standard 
• Safety Features: None 
• Finish Color: Flat Dark Earth 
• Condition: New in Box 
   

Detailed Features 

 
The striker-fired mechanism gives a consistent trigger pull without a manual safety. At 4.5 inches the barrel is on the longer side for a service pistol, which helps with velocity and sight radius. The suppressor-height sights clear most can sizes and remain usable with or without a suppressor attached. The FDE interchangeable backstrap lets you adjust the grip circumference to fit different hand sizes. Night sights are standard — useful for low-light defensive use without buying aftermarket sights. 
 

Target Audience 

 
The 509MT suits shooters who want a full-featured service pistol with a suppressor-ready sight picture. The FDE finish and 15+1 capacity make it practical for duty, home defense, or range use. 
 

Usage Scenarios 

• Home defense: 15+1 capacity and night sights are practical in low-light environments. 
• Tactical or duty use: the 4.5-inch barrel and suppressor-compatible sights match that application well. 
• Recreational shooting: reliable feeding across ammunition types and an adjustable grip suit extended range sessions.

The FN 509MT draws positive feedback for build quality and ergonomics. Owners describe the grip as comfortable and natural-feeling during longer sessions. Out-of-the-box accuracy is frequently noted — people report good results at defensive and medium ranges without needing to adjust sights. The 15+1 capacity is consistently cited as a plus for both carry and home use. Night sights are praised as a genuine advantage for self-defense setups.

The two main complaints are trigger feel and weight. Some owners find the trigger heavier and less refined than comparable pistols, and while the gun is well-built, the weight can make extended carry less comfortable. Holster availability is narrower than for Glock or S&W platforms, which comes up among people who want to carry regularly.