The FN 509 Midsize Tactical is a striker-fired 9mm pistol in Flat Dark Earth with a threaded barrel. The 4.5-inch threaded barrel is ready for suppressors or compensators without modification. Suppressor-height 3-dot night sights clear the top of common cans. Ambidextrous controls and interchangeable backstraps handle different hand sizes and shooter preferences. 
 

Key Specifications 

• Brand: FN 
• Model: 509 Midsize Tactical 
• Caliber: 9MM Luger (9x19 Para) 
• Action: Striker Fire 
• Capacity: 10+1 Rounds 
• Barrel Length: 4.5 inches (Threaded) 
• Weight: 1.74 lbs 
• Finish: Flat Dark Earth (FDE) 
   

Detailed Features 

 
The ambidextrous slide release and magazine release work for both right- and left-handed shooters without modification. The two interchangeable backstraps let you adjust grip circumference. The suppressor-height sights maintain a usable sight picture over common suppressor diameters. The FDE finish is a polymer/metal coating that resists wear in typical carry and duty conditions. 
 

Usage Scenarios 

• Home Defense: Suppressor-ready barrel and night sights are practical features for a firearm staged for low-light defensive use. 
• Sport Shooting: The 4.5-inch barrel and ergonomic layout work well for pistol competition formats. 
• Concealed Carry: At 1.74 lbs the weight is reasonable for a midsize pistol, though the threaded barrel adds length at the muzzle end.

FN 509 Midsize Tactical owners in 9mm consistently report positive experiences with build quality and reliability. The materials and finish hold up to regular use, and reliability complaints are infrequent in user discussions.

The threaded barrel is a frequently cited selling point — buyers who wanted a suppressor-capable pistol at this price point mention it specifically. The factory suppressor-height night sights are well-received for their out-of-box functionality.

Size and weight are generally positive notes. Shooters find it hits a reasonable balance between grip length for control and overall size for carry. Some users coming from compact pistols find it slightly heavier than expected.

Trigger opinion is split. Some describe it as smooth and consistent; others find it on the heavier or longer side compared to competitors and prefer an aftermarket option. Aftermarket support exists but isn't as deep as the Glock ecosystem, which some buyers mention as a drawback when looking for holsters or drop-in parts. Price-to-feature discussions are generally positive — most buyers feel FN delivers good value at its price point relative to comparable tactical pistol options.