The FN 509C is a compact striker-fired pistol chambered in 9mm Luger. It has a 3.7-inch cold hammer-forged barrel, holds 10+1 rounds, weighs 25.5 oz (1.6 lbs), and has a matte black finish. The slide includes an adapter plate for optics mounting. Interchangeable backstraps fit different hand sizes. 
 

Key Specifications 

• Brand: FN 
• Model: 509C 
• Caliber: 9MM Luger (9x19 Para) 
• Action: Striker-fired DAO (Double Action Only) 
• Capacity: 10+1 rounds 
• Barrel Length: 3.7 inches 
• Weight: 1.6 lbs (25.5 oz) 
• Sights: Open Notch Iron Sights 
• Optic Mount: Adapter plate included 
• Finish: Matte Black 
   

Detailed Features 

• Cold Hammer-Forged Barrel: Consistent bore, extended service life. 
• Striker-Fired Action: DAO trigger, consistent pull weight. No external safety required; the internal mechanisms handle drop and firing pin safety. 
• Optics Adapter Plate: Included from the factory. Mounts common red dot footprints without additional hardware. 
• Interchangeable Backstraps: Three sizes included; fit the grip to different hand dimensions. 
• Polymer Frame + Steel Slide: High-quality polymer and steel construction keeps the package at 25.5 oz unloaded.

The FN 509C in matte black gets favorable feedback across most user groups, including concealed carriers, range shooters, and those evaluating it for duty use.

The compact size carries well and handles comfortably during extended sessions. Grip ergonomics are consistently praised — the texture is described as effective and the backstrap options let shooters fine-tune the fit. Reliability with a wide range of ammunition is well-documented across owner reports.

The striker-fired DAO trigger gets mixed reactions. Proponents like the consistent pull and simplicity; some shooters find the pull weight heavier than they prefer for fast follow-up work. Aftermarket support exists but is thinner than Glock or M&P, which matters to those who want a specific holster or trigger component. Weight — at 25.5 oz — sits slightly heavier than some competing compact 9mms, which a few users note. The optics adapter plate as standard equipment is seen as a practical addition that avoids the need for a separate purchase when adding a red dot.