Training Replica: FNS-40 4"

The FNS-40 (4") represents FN�s first modern foray into the pure striker-fired market, departing from the hammer-fired designs of the FNP and FNX series. It was designed to provide a simpler, more "Glock-like" manual of arms while maintaining FN�s signature ergonomics and fully ambidextrous features. While the FN 509 has largely succeeded it in the current catalog, the FNS-40 remains a highly respected duty-grade firearm.

Key Design Elements

• Striker-Fired Action: Unlike the hammer-fired FN pistols you've looked at, the FNS is a true double-action striker system. It features a crisp trigger with a pull weight usually between 5.5 and 7.7 lbs and a very positive, tactile reset.

• Fully Ambidextrous: FN didn't cut corners here�the FNS-40 features a dual-sided slide stop lever and a dual-sided magazine release as standard equipment, making it one of the best choices for left-handed shooters.

• Cold Hammer-Forged Stainless Steel: Both the slide and the 4-inch barrel are stainless steel. The barrel is manufactured using the same rigorous processes as FN's military machine gun barrels, ensuring a long service life even with the snappier .40 S&W cartridge.

• Safety Options: The FNS-40 was famously offered in two configurations: one with a low-profile manual thumb safety and one without (standard duty model).

• Interchangeable Backstraps: The frame includes two backstraps (flat and arched) to allow the user to change the grip angle and reach to the trigger.

Current Status (2026)

As of 2026, the FNS-40 has been discontinued from FN's primary commercial production, as the FN 509 is now their flagship striker-fired platform. However, it remains widely available on the secondary market.

FNS-40 vs. FN 509

• The Evolution: The 509 is essentially an "FNS 2.0." FN made over a hundred internal and external improvements to the FNS design to meet the U.S. Army's MHS requirements, leading to the 509.

• Compatibility: While they look similar, many parts (including slides) are not interchangeable. However, many holsters designed for the FNS-40 will fit the 509 and vice versa, depending on the manufacturer.

• Magazines: Good News: The FNS-40 and FNX-40 share the same magazine pattern, making spare magazines much easier to find than the older FNP series.

Technical Specifications

Performance Notes

The FNS-40 is known for its aggressive grip texture. While it ensures the gun won't slip out of your hand during the "snappy" recoil of a .40 caliber round, some shooters find the checkering a bit sharp for extended range sessions without gloves.