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FN Herstal’s FN 509: The Gun the U.S. Army Said No To

FN 509
FN 509 (Image courtesy of manufacturer.)

Though the Fabrique National’s FN 509 pistol is a solid design, it had one shortcoming: no ammunition package deal.

The Army’s XM17 Modular Handgun System Competition

The U.S. Army‘s now-completed Modular Handgun System competition sought to replace the venerable Beretta M9 pistol as the standard-issue American service pistol. Though the pistol was certainly a superior firearm when introduced in U.S. service in 1985, pistol design had improved since the Regan era, necessitating a replacement for the U.S. Army, as well as the other service branches that fielded the M9. Enter the XM17 Modular Handgun System competition.

Contenders vying for the Modular Handgun System (MHS) Competition represented some of the oldest, most respected, and well-known firearms manufacturers in the world, each of which would attempt to unseat Beretta as the handgun supplier of choice for the United States. In addition to FN Herstal, Glock, SIG Sauer, CZ, Smith & Wesson, and of course the incumbent Beretta entered the competition.

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Each firm submitted exceptional pistol designs with Sig Sauer ultimately winning the contract. Interestingly enough, many of the losing firms have sold hundreds of thousands of their MHS pistols despite losing the competition, a testament to the high quality of pistols, and how stiff the competition would be.

Fabrique National Herstal

Today, some of Fabrique National Herstal’s more well-known designs include the P90 bullpup submachine gun-turned-personal defense weapon, or their Five-seven pistol, both of which are chambered in the unique 5.7×28mm cartridge. The 5.7×28mm cartridge is a small-caliber, high-velocity cartridge that was evaluated — but not selected — by NATO as a replacement for the ubiquitous 9×19 Parabellum pistol cartridge and is known for its good stopping power.

Though perhaps lesser-known, FN Herstal’s FN 509 is no slouch either.

FN 509 in Black

FN 509 in Black (Image courtesy from manufacturer).

FN 509

FN Herstal’s FN 509 is based on their earlier FN FNS design, and their entrant appeared to be promising. It sported a 4.5-inch cold hammer-forged stainless steel barrel that was also threaded to accept a sound suppressor. The pistol’s sights were correspondingly raised to allow for accurate shooting if a suppressor was equipped.

Interestingly, the FN 509 design also features a so-called slide cap, essentially a removable slide extension with sight wings that protect the rear sights from misalignment due to being accidentally dropped or otherwise jostled. In addition, the chunky wings are textured and allow for one-handed slide racking.

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In addition to somewhat small 10-round magazines, the FN 509 could also be equipped with larger 17-round magazines, or quite large 24-round magazines, both of which protrude from below the bottom of the pistol’s grips. The pistol’s backstops are removable to fit a variety of hand sizes. The pistol also featured ambidextrous magazine releases and side stop levers.

It was in a word, competitive — though it didn’t win.

Down and Out

Ultimately, FN Herstal’s pistol wasn’t selected. Instead, the Army selected SIG Sauer’s M17 and M18 pistols. Though it could be argued that SIG Sauer’s design was marginally better than FN Herstal’s what really set SIG apart from the competition was its ammunition.

SIG partnered with Winchester to offer the Army a package deal: in addition to their pistol designs, the Army would also have access to two types of Winchester ammunition. The two cartridges are said to be superior that standard-issue 9x19mm ball ammunition and the offer just couldn’t be sweeter.


Though FN Herstal’s FN 509 pistol is no slouch and has proven to be a commercial success for the company on the civilian market, it just couldn’t compete with SIG’s pistol and ammunition combination. 

Caleb Larson is a Defense Writer with The National Interest. He holds a Master of Public Policy and covers U.S. and Russian security, European defense issues, and German politics and culture.

Written By

Caleb Larson, a defense journalist based in Europe and holds a Master of Public Policy degree from the Willy Brandt School of Public Policy. He lives in Berlin and writes on U.S. and Russian foreign and defense policy, German politics and culture.



  1. Ed

    December 22, 2020 at 1:25 pm

    Sorry, but this was a weakly researched piece that said little more than Sig and Winchester were friends. Since Winchester is an independent company, why not just buy the ammo from Winchester and cut Sig’s margins out of the deal? Why didn’t other manufacturer’s integrate the Winchester ammo in their offer? The gov’t request for a sidearm didn’t require ammo so the two were two separate deals then anyway. What was special about Winchester’s ammo that Hornady’s self-defense rounds couldn’t do (except maybe be legal as warfighter ammo)?

    The article raised more questions and provided little researched specific answers.

    Not the least of which is how anyone could think the P320 is a better gun than the P229, or P226…outside of cost.

  2. Shawn

    December 23, 2020 at 12:42 pm

    FN’s 5.7x28mm cartridge “is known for its good stopping power”? Tell that to US law enforcement agencies that actually used it in shootings. They referred to violent felons shot with it as “bullet sponges” because it required many rounds to stop them. Jacksonville, FL, PD used it in several shootings and was highly disappointed in its “stopping power”. Also, its use during the 1996 Japanese Embassy Hostage Crisis in Lima, Peru, provided an early indicator of its poor “stopping power”.

  3. PVT Bells Van Farnum

    October 12, 2021 at 11:57 pm

    The M9 was a Toyota Corolla. The Colt and Springfield 1911s were muscle cars, and the way to go 15 and in. If modified and properly cared for, they can’t be beat. I would have liked to see an offering close to a 1911. Not a 2011 because those are dumb. I put tens of thousands of rounds through my 1911 in the early 2000s. But I got out to raise a family, the military got bit by woke zombies and traded in their balls, so this is what you get… a polymer Sig in 9mm.

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