The FNH FNX 40 is a full-size, hammer-fired .40 S&W pistol designed for law enforcement, home defense, and professional use. It features a double-action/single-action (DA/SA) trigger system, stainless steel slide, polymer frame, and ambidextrous controls, combining modern ergonomics with traditional double-action reliability.
With 10- or 14-round magazine options, a 4-inch cold hammer-forged barrel, and a reputation for durability, the FNX 40 stands as one of the most robust .40 caliber pistols FN America has ever produced.
When FN Herstal released the FNX 40, it continued a legacy of battle-proven engineering rooted in military and law enforcement service. Manufactured by FN America in Fredericksburg, Virginia, the FNX series represented a refinement of the earlier FNP line — integrating improved ergonomics, ambidextrous controls, and a modern polymer frame optimized for both right- and left-handed shooters.
While striker-fired pistols dominate today’s market, the FNX 40 retains a traditional hammer-fired DA/SA system, offering the combination of a long, deliberate first trigger pull for safety and a short, crisp single-action follow-up. This system appeals to shooters who prefer a mechanical safety margin without relying solely on passive trigger safeties.
Aimed primarily at law enforcement, home defense, and security professionals, the FNX 40 offers serious stopping power with the .40 S&W cartridge — a round long trusted for duty use. Despite being discontinued, it continues to attract loyal users who value its reliability, ambidextrous versatility, and controllable recoil dynamics.
FNX 40 Specifications
FNX 40 Design & Build Quality
Construction
The FNX 40 showcases FN’s commitment to quality manufacturing. The polymer frame incorporates replaceable steel slide rails, providing the durability of an all-metal pistol with reduced weight. Its stainless steel slide, finished in matte black, resists corrosion and wear while featuring front and rear cocking serrations for easy slide manipulation.
The cold hammer-forged barrel offers exceptional strength and longevity — a hallmark of FN craftsmanship. The polished chamber and feed ramp ensure smooth, consistent feeding with various ammunition types.
Ergonomics & Grip
FN engineered the FNX 40 for comfort and control under recoil. The checkered and ribbed grip panels provide a secure, non-slip surface, while the interchangeable backstraps allow shooters to tailor the grip size to their hand. Despite its full-size frame, the ergonomic shaping makes it manageable for medium-sized hands.
The grip angle naturally points on target, similar to the 1911, and aligns quickly during rapid draw and presentation.
Controls
A defining feature of the FNX 40 is its fully ambidextrous control layout — including decocker/safety lever, slide stop, and magazine release. This makes it a strong choice for left-handed shooters or agencies standardizing across diverse users.
The decocking/safety lever allows the pistol to be carried in multiple modes:
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Hammer down (DA mode) for a long, deliberate first pull
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Cocked and locked (SA mode) for a 1911-style single-action draw
This flexibility is rare among modern polymer-framed pistols and adds a layer of versatility many shooters appreciate.
Accessory Compatibility
The integrated MIL-STD-1913 Picatinny rail supports a wide range of tactical lights and lasers. While the FNX 40 isn’t optics-ready from the factory, aftermarket slide milling for red dots has become increasingly common among enthusiasts.
FNX 40 Variants & Model Differences
The FNX 40 is part of FN’s broader FNX series, which includes:
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FNX 9 — 9mm version with identical dimensions and ergonomics
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FNX 45 — .45 ACP version with a slightly larger frame and higher capacity
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FNX 45 Tactical — optics-ready variant with threaded barrel and suppressor-height sights
The FNX 40 was designed as a duty-sized pistol, not offered in compact or subcompact configurations.
Comparable Firearms
When introduced, the FNX 40 competed with several DA/SA polymer-framed pistols, such as:
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HK USP40 — Known for durability and similar control layout, but heavier and more expensive
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Sig Sauer P229 (.40) — Comparable accuracy and trigger refinement, but smaller capacity
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Beretta PX4 Storm — Rotating barrel design reduces recoil, but ergonomics differ significantly
Compared to these, the FNX 40 is often described as the best value DA/SA polymer pistol in its class — offering ambidextrous usability and high capacity at a lower price point.
Performance
Accuracy
The FNX 40 delivers excellent accuracy for a .40 S&W duty pistol. Real-world testing and user reviews report 2- to 3-inch groups at 25 yards, with the crisp single-action trigger enabling tight follow-up shots.
The fixed 3-dot sights provide a clean, visible sight picture, and optional tritium night sights enhance performance in low-light defense scenarios.
Recoil & Control
Despite firing the snappier .40 S&W cartridge, recoil is well-managed thanks to FN’s low bore axis and robust frame design. The slide’s mass helps absorb energy, and the textured grip ensures the pistol stays planted during rapid strings of fire.
Shooters often note that while the recoil impulse is sharper than a 9mm, it remains linear and predictable — allowing for fast sight recovery.
Reliability
Reliability is where the FNX 40 shines. FN pistols undergo extensive endurance testing, and user reports mirror that reliability. Even after 2,000+ rounds of mixed ammunition, the FNX 40 runs without notable malfunctions when properly maintained.
The polished chamber and feed ramp reduce failures to feed, and the external extractor ensures positive ejection.
Trigger Quality
The DA/SA trigger system is traditional but effective. The double-action pull averages around 10 pounds, smooth but long — requiring familiarization for precision. Once in single-action, the break is crisp at roughly 4.5 pounds with a tactile, short reset that rewards disciplined shooters.
For those accustomed to striker-fired pistols, the transition may require adjustment, but seasoned shooters appreciate its control and safety benefits.
Ammunition Compatibility
The FNX 40 feeds virtually any quality .40 S&W ammunition reliably.
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Ideal grain weights: 165–180 grain projectiles
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Defensive loads: Federal HST, Speer Gold Dot, and Winchester Ranger T are excellent choices
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Training loads: Blazer Brass 180gr FMJ and Winchester White Box function flawlessly for range sessions
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+P loads: The pistol can handle limited use of +P ammunition, though FN does not recommend exclusive +P use for longevity
A few isolated reports mention light primer strikes with lower-quality reloads, but factory ammunition performs flawlessly.
Use Case Suitability
Concealed / Self-Defense
While possible, the FNX 40’s full-size frame and 1.55-inch width make it challenging for everyday concealed carry. It’s best suited for open carry, duty rigs, or winter concealment under outerwear.
Home Defense
This is where the FNX 40 truly excels. The .40 S&W caliber provides strong stopping power, and the 14-round magazine offers solid capacity for defensive scenarios. Paired with a weapon light on the accessory rail and night sights, it’s a formidable home defense handgun.
Competition (IDPA/USPSA)
The FNX 40 can perform in practical shooting competitions, though its DA/SA trigger may slow initial shots compared to striker-fired competitors. Still, in experienced hands, it’s accurate, consistent, and fast in single-action stages.
Outdoor / Field Use
The robust polymer frame and corrosion-resistant stainless components make it ideal for field use or as a vehicle/ranch sidearm. The .40 S&W cartridge provides enough energy for defense against medium threats, including feral animals.
Range Use
While it’s overbuilt for casual plinking, the FNX 40’s controllable recoil and reliability make it a satisfying range gun for shooters who appreciate the DA/SA experience.
Best Holsters for FNX 40
Finding the right FNX 40 holster ensures secure retention, balanced draw speed, and comfortable carry whether you use it on duty, at the range, or for home defense setups.
Cloak Tuck 3.5 IWB Holster
The Cloak Tuck 3.5 IWB holster for the FNX 40 holster offers deep concealment and custom adjustability. It balances comfort and stability for those carrying a full-size pistol inside the waistband.
Belt Holster
A belt holster for the FNX 40 holster provides excellent retention and accessibility for open or range carry. It distributes weight evenly and supports a smooth, natural draw.
OWB Paddle Holster
The OWB paddle holster for the FNX 40 holster offers quick on/off convenience for range sessions or open carry. Its wide paddle base provides stability during active movement or training drills.
Swivel Drop Leg Holster
A swivel drop leg holster positions the FNX 40 holster lower on the thigh for tactical or duty setups. This placement enhances draw speed when wearing vests or outer gear.
Chest Holster
Chest holsters for the FNX 40 holster are ideal for vehicle carry, hiking, or outdoor use. They keep the firearm accessible while keeping your waist clear for packs or equipment.
Hook & Loop Holster
Hook & loop holsters allow flexible mounting for the FNX 40 holster in vehicles, bags, or modular systems. This option is ideal for secure but rapid access in confined spaces.
FNX 40 Pros & Cons
Pros:
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Excellent reliability and durability under high round counts
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Crisp single-action trigger with short reset
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Fully ambidextrous controls for universal usability
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Comfortable, customizable grip with backstrap options
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Cold hammer-forged barrel ensures longevity and accuracy
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MIL-STD-1913 rail supports lights and lasers
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Corrosion-resistant materials and easy field stripping
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High magazine capacity for a .40 S&W
Cons:
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Heavy double-action trigger pull for first shot
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Large frame not ideal for concealed carry
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Limited aftermarket accessory support
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Discontinued, so parts may require sourcing through FN
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Slightly heavier recoil than comparable 9mm models
Final Verdict
The FNX 40 exemplifies FN America’s engineering philosophy — robust, accurate, and built to perform under pressure. While it may not have the trendy appeal of today’s striker-fired compacts, it remains a professional-grade sidearm with battle-ready reliability and precision.
Value for money:
On the used market, the FNX 40 represents outstanding value. For around the cost of a budget striker pistol, you get a full-featured, ambidextrous, DA/SA firearm with military-grade construction.
Long-term ownership:
Its stainless steel internals, polymer frame, and simple takedown ensure longevity and ease of maintenance. FN America continues to provide service support for the FNX line.
Ideal for:
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Shooters preferring the control of DA/SA triggers
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Home defenders wanting power and reliability
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Law enforcement professionals or armed security
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Enthusiasts who value craftsmanship and longevity over trend
FN & FNH Handgun Guides and Reviews
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• FNH Five-Seven Guide: Complete Overview
• FNH 502 Guide: Tactical .22 LR Insights
• FNH 503 Gun Guide: Micro-Compact Carry Review
• FN 509 Overview: Duty-Ready 9mm Platform
• FNP-40 Guide: DA/SA .40 S&W Breakdown
• FNP-45 Guide: Heavy-Duty .45 ACP System
• FNP-9 Guide: Features, Specs & Insights
• FNS-40 Guide: Striker-Fired .40 Review
• FNS-9 Review: Accuracy & Ergonomics Breakdown
• FNS Compact Review: Concealed-Carry Performance