The FN FNX-9 is a 9mm DA/SA semi-automatic pistol with a 4-inch cold hammer-forged stainless steel barrel, polymer frame, and 17-round capacity. It ships with two magazines. 
 

Key Specifications 

• UPC: 845737000103 
• Caliber: 9MM Luger (9x19 Para) 
• Action: Double Action/Single Action 
• Capacity: 17 Rounds (Includes 2 magazines) 
• Barrel Length: 4 inches 
• Overall Length: 7.4 inches 
• Weight: 1.4 lbs (21.9 oz) 
• Frame Material: Polymer 
• Finish Color: Black 
   

Detailed Features 

• DA/SA trigger with ambidextrous decocking safety lever — first shot double action, subsequent shots single action after cocking the hammer. Works equally for right- and left-handed shooters. 
• Cold hammer-forged stainless steel barrel for consistent accuracy and durability over high round counts. 
• External extractor doubles as a loaded chamber indicator — visible and tactile check without opening the action. 
• Interchangeable backstraps (three sizes included) for hand-fit customization. 
• Fixed three-dot sights standard; night sight version available. 
• Ambidextrous controls throughout: slide stop, magazine release, and decocker. 
   
  The FNX-9 is on the larger end for a 9mm full-size, which is a tradeoff for the 17-round capacity and the DA/SA mechanism's longer trigger reach in DA mode. At 21.9 oz empty it's not particularly heavy for the platform.

The FNX-9 earns consistent positive marks from owners, particularly on reliability and ergonomics.

Grip feel and fit get the most direct praise. The interchangeable backstraps make a genuine difference for shooters with larger or smaller hands, and the textured polymer frame gives a secure hold. It's one of the more comfortable full-size 9mm pistols to hold extended.

Reliability with varied 9mm loads is widely reported as solid. Function issues are uncommon in owner accounts.

The 17-round capacity is a practical advantage, cited frequently by owners who use it for home defense or range work.

The DA/SA mechanism gets mixed feedback. Shooters who prefer a consistent pull across all shots — or those coming from striker-fired platforms — sometimes find the transition between DA and SA disorienting until they practice the first-shot DA pull deliberately. Owners who came from traditional DA/SA pistols (Beretta, SIG) adapt quickly.

Size is the main practical objection. The FNX-9 is bulky for concealed carry, and most owners are candid about that. It works well as a home defense or range pistol but requires a deliberate holster and clothing choice for carry.

The polymer frame doesn't bother most owners functionally, though a small number note it feels less premium compared to metal-framed alternatives at higher price points. Durability complaints are not common.