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After several years of planning, requests, delays and testing, the XM17 Modular Handgun System competition is finally over. Several firearms manufacturers participated in the program by developing new pistols with modern designs and enhanced features that were part of the Army and Air Force’s request for proposals. 

Aside from the military, the beneficiaries of the MHS competition are civilians, because those new models are working their way into the civilian marketplace. One company that participated in the program and developed its own new pistol design for the competition is Fabrique Nationale. FN has been in business for more than 125 years and is one of the most well-known firearms manufacturers in the world—particularly when it comes to military weapons such as the M249 and M2 .50-caliber machine gun.

Although the 509 looks very much like the FNS series, the pistol has been reworked in multiple ways to make it a serious upgrade.

Famous models produced by FN that most gun enthusiasts are also familiar with include the Browning Hi-Power, Auto-5 shotgun, FAL, SCAR and PS90. This manufacturer’s latest design, the FN 509, is a result of FN’s entry into the MHS competition. While not exactly the submission pistol, it’s close enough to get an idea of the design it chose for its MHS solution: The FN 509’s basic design stems from FN’s previous FNS series of pistols, although such a significant amount of refinement and enhancements were done that it is a significant evolutionary step over its previous line of striker-fired pistols.

THE FN 509

Like its FNS predecessors, the 509 is a striker-fired polymer pistol that is chambered for 9mm Parabellum, although that could change down the road, because more variants/chamberings could be produced. Some visual cues remain from the FNS line, but multiple changes were made to improve accuracy, reliability, handling and durability of the 509. Before getting into those changes, it’s worth noting that the 509 is a hybrid design of sorts.

“One of the key selling points of the FN 509 is FN’s statement that more than 1 million bullets were fired during its development.”

The 5.56-inch height of the pistol allows it to carry a 17-round magazine similar to full-sized pistols on the market. However, the barrel length is only 4 inches—typically a length reserved for what most companies consider compact pistols. One of the most noticeable changes when you look at and pick up the 509 is the texturing on the grip area. Even though it is still present, FN’s pyramid texturing has been moved from the front and back straps to the side panels in an effort to satisfy customer feedback. The texturing on the front and backstraps is now a milder form that still provides secure retention of the pistol but is not as uncomfortable on the user’s hand while gripping the weapon.

The cocking serrations are beautifully engineered with both an aggressive depth and greater width, thus allowing for an easier grip to press-check the weapon.

Speaking of backstraps: FN currently offers two models of the FN 509: a civilian version and the law enforcement version. The civilian version offers two interchangeable backstraps to modify the size of the grip for different-sizes hands. However, the law enforcement version offers three backstraps instead of two, offering an additional size for the user with larger hands. Other amenities included with the law enforcement model include three magazines instead of the two with the civilian version. Also, tritium night sights are included, where just luminescent sights are available on the civilian offering. The sights are nice and are a standout feature on the 509, aside from the luminescent treatment. They are a large (high), three-dot variety that are very easy to pick up to quickly engage the target, although they are not as well suited for nighttime use as the tritium version.

Changes were made to the magazines to again enhance the performance of the pistol. The 509’s magazine has a redesigned floorplate that makes it easy for the user to rip the magazine out of the pistol if it does not drop free on its own.

The FN 509 has a 5.79-inch sight radius to help with more-accurate shot placement.

The magazines of the 509 will work on the full-sized FNS pistol, but the reverse is not true, unless the user buys the new floorplates for their FNS magazines and then makes them compatible with the 509.

Another enhancement over the FNS series comprises the slide serrations on the 509. They are located at both the front and the back of the slide and are some of the best executions of serrations I’ve seen. They are angled, spaced widely apart and quite aggressive, making grasping the slide a fluid and almost natural process.

The 509 is a more robust tool for longer durability, as is evidenced by this beefier locking block.

Despite the aggressive nature, they are not uncomfortable in the least. Also adorning the 509 is the MIL-STD-1913 Picatinny rail for accessory attachment. One aspect of the 509 a lot of people are going to like is the ambidextrous nature of the pistol. It has both an ambidextrous slide catch/release and magazine release. A nice bonus is the ease with which the right-hand slide catch/release works on the 509 for left-handed shooters.

Sometimes, with an ambidextrous release, one side doesn’t work as well as the other—most often the right-hand side. FN did a great job in designing this feature; both sides work equally as well, allowing lefties to enjoy the same shooting experience as the rest of the population.

The FN 509 incorporates a MIL-STD-1913 Picatinny rail for the addition of accessories such as lights and lasers.

The FN 509 does have an external extractor that some might consider to be a better implementation than an internal extractor. It also acts somewhat as a loaded chamber indicator as the rear of the extractor angles inward slightly when a round is in the chamber, so the user can get a tactile sense of the pistol’s status. However, the extractor does not stick out prominently in the front, making it hard to feel. Also, when angled outward, it reveals a small bit of red paint, but it’s not highly visible and really of little use in real-world conditions.

The sights are tall—almost suppressor height—and are of a three-dot variety that is easy to pick up in daylight conditions.

An interesting addition to the pistol in comparison to most combat pistols on the market is that the barrel sports a recessed crown. By recessing it, it is more protected from drops and other mishaps. Additionally, the cold, hammer-forged stainless barrel—and the stainless slide, for that matter—are treated with a nitro-carburizing finish that is more durable than finishes FN has used in the past.


One of the key selling points of the FN 509 is FN’s statement that more than 1 million bullets were fired during its development. While the majority of that ammunition was expended during the MHS phase, FN also interacted with different law enforcement agencies about the type of ammunition they use to ensure the 509 was reliable with what was being used in the commercial market.

DSG Arms’ Compact Discreet Carry holster and double magazine carrier make for an excellent appendix rig for the 509.

My own testing fell a little short of a million rounds, but I shot enough to get a feel for what the 509 was capable of and was impressed overall. The handling of the 509 was excellent, and the redesign of the texturing paid off. I found the grip was extremely comfortable, yet it was still quite grippy for a secure purchase on the pistol. For use with the FN 509, I received DSG Arms’ excellent Compact Discreet Carry model holster, along with one of its double-stack mag carriers. The execution of these products was top shelf, and I used them on the range, as well to carry the 509 concealed during the test period.

DSG Arms’ CDC holster and mag carriers are top-quality accessories that are user adjustable for cant and retention.

I must say, the CDC was extremely comfortable, and the ability to adjust the cant of the holster made it more versatile to carry in multiple positions around the waistline, including up front for appendix carry.

The retention on the firearm was great, because it is user adjustable to one’s preference. DSG Arms is definitely an outfit you want to consider for your next holster purchase. It offers substantial quality with a competitive price.

For general shooting, I used Fiocchi’s 124-grain FMJ rounds, from which I’ve gotten good results in the past. During the first 400 rounds, I did not experience a single malfunction of any kind. No break-in period was required, and I liked that.

After that, I ran 150 rounds of hollowpoints through the pistol for function testing.  They included SIG Sauer’s 124-grain Elite V-Crown, Federal Premium’s 124-grain HST and the 124-grain Colt National Match produced by DoubleTap. As with the ball ammo, no failures were experienced with the premium ammunition. One thing I did notice while running a few drills is that I didn’t like the magazine release. Because there is a button on each side, when I depressed one side, the other side stuck out and bumped my fingers. At times, this caused me to not fully engage the magazine release without significantly shifting my hand’s position on the pistol. My druthers would be to have a single button that is user reversible for a much simpler process. On the other hand, one aspect of the 509 I found to be exceptional was the accuracy of the pistol. Not only did I experience tight groups offhand, but I got some pretty impressive results from the bench, as well.

Even though the 509 had a compact, 4-inch barrel, I felt it was more of a duty weapon, so I tested it that way. Usually, I test compact at 15 yards, but I went the full 25 yards to see how the 509 could do. It did quite well. The average size of all groups fired with the premium ammunition was 2.31 inches from the compact shooting rest.

This 1.88-inch group at 25 yards was obtained with Federal Premium’s 124-grain HST load.

The best single five-shot group was with Federal’s 124-grain HST loads, coming in at just 1.88 inches; and the Federal load also got the best average group size, at just 2.09 inches at 25 yards.

Whether the planets were aligned just right, I do not know, but for me, an average group that size at 25 yards is outstanding. That’s not to say there wasn’t a bit of struggle for me in shooting those groups. I had noticed during my “general” shooting session that the trigger had that gritty, polymer-on-polymer feel. It did smooth out some over the course of approximately 600 rounds fired, but it never got to the point where I would consider it excellent—although an argument could be made that the trigger was developed for use in the service, for which a heavier trigger is sometimes preferred. After I was done shooting the FN 509, I used the Lyman digital scale again to see what the average trigger pull was. I was surprised that it was 5.63 pounds.

For whatever reason, it just felt heavier than that, even though it was serviceable—as evidenced by the spectacular groups that were obtained. I have heard that a couple of aftermarket companies are considering making triggers for the 509, so this may become a moot point for those willing to pony up the extra cash.


The FN 509 is a serious upgrade to the FNS line of pistols, and one of the factors that helped this development along was the XM17 MHS competition.

As we’ve learned in the past, competition results in better products for consumers, and that’s the case with this product, as well. We could not touch on every single tweak or enhancement made in this article, but even the ones we’ve listed significantly improve FN’s offerings regarding its polymer striker-fired pistols lineup.

The handling is excellent, as is the accuracy. Other touches, such as the robust build quality, aggressive slide serrations and ambidextrous controls, make the 509 an extremely competent combat weapon.

Even though there are a few niggles here and there, FN has an excellent pistol on its hands, and it is sure to see great demand. This company has provided just about every improvement people have requested in a combat pistol, and it’s the complete package. If you’re in the market for a cutting-edge, modern-day fighting pistol, give the 509 a try. It could be exactly what you’re looking for.



Velocity (fps)

Accuracy (inches)



SIG Sauer 124-grain Elite V-Crown




Federal Premium 124-grain HST




Colt 124-grain National Match (Double Tap)




NOTES: Bullet weight was measured in grains. Velocity was measured in feet per second (fps) 15 feet from the muzzle by a Competition Electronics ProChrono Digital Chronograph. Accuracy was in inches for three five-shot groups at 25 yards.




BARREL: 4 inches
OVERALL LENGTH: 7.4 inches
WEIGHT: 26.9 ounces (empty mag)
WIDTH: 1.335 inches
HEIGHT: 5.56 inches
GRIP: Polymer, adjustable
SIGHTS: Three-dot luminescent
ACTION: Semiautomatic
FINISH: Nitrocarburizing
CAPACITY: 17+1 rounds
MSRP: $649




Editor’s note: A version of this article first appeared in the November 2017 print issue of Gun World Magazine.