FN 509 9mm Striker-Fired Pistol Review

FN 509 9mm Striker-Fired Pistol Review

Competition improves the breed. It is fashionable in some circles to mock competition as unrealistic, but the problem-solvers who compete drive improvements from which we all benefit. In this case, the driver was the U.S. Army and its Modular Handgun System (MHS) program. The M9 was said to be long in the tooth, and a lot has changed since its adoption more than 30 years ago. The Army wanted something different. They wanted something that would work with suppressors, a pistol that could be easily reconfigured for various hand sizes and missions. And along those terms, the Army also wanted a pistol flexible enough to host lights, lasers, slide-mounted red dots, etc.

The specs of the pistol are pretty impressive. The Army insisted on a 90 percent or greater chance of a hit from the MHS candidates on a 4-­inch circle at 50 yards. A stoppage rate of no more than one per 2,000 rounds was insisted upon, as was 10,000 rounds between failures and a service life of 35,000 rounds. And the MHS submissions had to handle a 20 percent increase over SAAMI pressure specifications without a decrease in reliability, safety or service life.

Knowing that ammunition developers were making strides in improving performance capabilities with regard to different calibers, bullet size was left open when Big Army sent out its request for proposal (RFP). FN decided to go for it and chased the MHS competition to its finish.

FN's MHS submission began with the existing FNS compact, which is a striker-fired pistol. The result of years in development and testing produced the pistol reviewed here: the FN 509. Like its competitors, the 509 is a large-capacity 9mm.


The slide is milled from a stainless steel bar and machined with angled cocking serrations at the front and rear. The top of the slide is flat with a raised rib down the center. The edges of the slide are rounded to prevent snagging or uncomfortable handling.


FN 509 rear sight
Three-­dot, phosphorescent-painted notch and post night sights glow green after exposure to light. Each sight is dovetailed into the top of the slide. Aggressive cocking serrations are on both sides of the slide's front and rear.

The sights on top of the slide are both drift adjustable- and they are sturdy and made of steel. When aligning them, you'll notice its three-­dot sight layout. Those sights might appear white, but they're actually painted with a phosphorescent paint that's charged by exposure to light, and they appear green in low-light or no-light conditions. The version of the 509 that's offered to law enforcement agencies can be ordered with optional tritium night sights. It's worth noting that the rear sight is designed so that we can easily use the vertical front face as a one-handed slide-­racking point.

The slide flats forward of the ejection port are machined with a slight taper to the top to make reholstering smoother. The angled and lowered surfaces of the ejection port are also cleverly cut to provide spent cases a clear path out of the slide. The flare at the front of the ejection port allows shooters to more easily clear the nose of an unfired round.

As with the other MHS contenders, the 509 operates using a striker-fired system. The slide also contains a passive firing pin/striker block safety to preclude unintentional detonations that might otherwise occur if it were dropped or struck in just the right manner.

The cold-hammer-forged (CHF) barrel is of FN's own manufacture and measures 4 inches. It's a simple drop-in design with an integral feed ramp and a recessed crown. FN manufactured the muzzle to ensure that the bullet cleanly exits the bore, and that the lands and grooves are protected from incidental contact.


FN 509 slide
As a product made to meet the specs outlined in the MHS solicitation, the FN 509 barrel is certainly ready for use with +P ammunition and will undoubtedly handle it better than some shooters. (The recoil can be stout in the 509, though this model is chambered in just a 9mm.)

The barrel cams down and back up on a steel block pinned to the polymer frame. All of this is the modern normal with similar striker-fired pistol designs. Also, the polymer frame of the 509 features different nonslip textures molded around the grip. At the front of the frame is the dustcover, which extends to the muzzle and offers us an accessory rail. Look at the rail from underneath, and you'll find the pistol's serial number. Since the serial number plate is permanently bonded to the rail and frame, this is not considered one of the new removable, or modular, chassis designs.

FN 509 barrel
The front of the slide and dustcover are beveled to facilitate effortless reholstering, while the Picatinny rail will accept a multitude of lights and aiming lasers.

The triggerguard on the 509 is large and easy to use with gloved hands. This is important for armed professionals and those who carry in colder climates. We used to think of gloves as cold-­weather garments, but we are also seeing them worn as protection against heat. Anymore, a new sidearm that can't be used with gloves isn't of much interest.

The frontstrap sports an aggressive nonslip square-bit pattern that FN calls "Dragon Scales." The backstrap wears the same square-bit pattern and can be replaced with a larger or smaller back panel for ideal user fitment.


The sides of the grip below the magazine release are molded with FN's pyramid-pattern texture, which is a second nonslip surface especially designed to keep water or sweat from making the grip slick. Thirdly, there's a more subtle stippled pattern that FN calls "Skate Tape" for where they want our thumbs to ride. These three patterns make the grip of the 509 very tactile.

FN 509 magazines
The 509 offers a 17+1 magazine capacity and utlizes steel drop-­free magazines with fully welded spines. FN's signature pyramid-frame texturing covers each grip panel.

The magazine release is familiarly located at the rear of the triggerguard and above the raised frontstrap. Rather than being reversible, this is one of the few magazine release buttons on the market that's immediately ambidextrous. Great move, FN.

You may note that the bottom of the grip's side flats feature scallops that encourage shooters to find and gain leverage over a damaged magazine's baseplate should they need to remove it in an emergency.

The top of the frame matte flats is where FN placed the ambidextrous slide stop. The two tabs - one on each side - are slightly guarded from unintended brushups by a raised rib that surrounds the lever. This fence around the serrated lever also keeps us from inadvertently pushing the slide to lock open before running out of ammunition in our magazine. (Admit it, we've all done it.) However, these molded lever guards won't obstruct the effort should you prefer to run the slide forward by using the lever as a slide release rather than slingshotting it.

The tang of the frame is nicely shaped to distribute recoil across the palm of our hands, and the beavertail protects the web from being bitten by a reciprocating slide. (Of course, arguably the best feature of a striker-fired gun is that it doesn't have a hammer, which means that we won't suffer hammer bite in the 509 as well.) The curvature FN has engineered allows a high enough grip on the frame that we can easily manage the recoil, even from the snappiest +P loads.

FN 509 serial number
The serial number plate is permanently bonded to the frame, closing the door on replaceable grip frames.

As previously mentioned, the FN 509 offers an interchangeable backstrap system that affords users the option to alter the girth of the grip's circumference. The backstrap is held in place by a rollpin crossways to the frame, which, unfortunately, means that we have to use tools such as a hammer and punch to test the feel of each backstrap.

Each molded backstrap also contains the lanyard loop attachment point. The design is simple, and replacement backstraps are likely inexpensive. We'd enjoy experimenting with these parts as we explore different texture styles and patterns. If you don't find one that works better, you can easily reinstall a factory backstrap.

My first thought when I saw the 509 was, Oh, goody. Another polymer pistol. No doubt it's going to have a bad trigger and no soul. And then I picked it up.

Hmmm, I thought. This feels pretty good! I put the 509 down and picked it up again - and it still felt good in my hand. I spent my first day just handling it and inspecting the various details. I kept picking it up and putting it down, and it was noticeably comfortable. In speaking with other editors on the G&A staff, it seems that I'm not alone in my observations.

The trigger has a clean and soft takeup. Then it stops and does not move until there's enough pressure applied to fire the striker. There's no grit, no crunchy travel and no spongy trigger movement as the pressure builds.

FN 509 performance
And the magazine? We get 17 rounds of Parabellum goodness. The magazine is steel with a fully welded spine, witness holes for quick inventory and a removable baseplate (evidence that FN is thinking of capacity extensions). The magazine catch is a tab on the front of the tube that works with the ambi magazine catch. On the right side of the magazine tube, you'll notice a punched ­out stop tab that keeps the magazine from going up too far into the frame. If you happen to do a speed reload with the slide locked back, that tab will stop the magazine.

Takedown of the FN 509 is easy. Lock the slide back and make sure it is unloaded. Remove the magazine. Rotate the disassembly lever on the left side of the frame. Press the slide stop down and ease the slide forward. Like a Glock, the trigger must be pressed before the slide can be removed.

FN 509 ranks high due to performance
Of the many striker-fired, polymer-framed 9mm pistols introduced in the wake of the MHS competition, G&A's staff ranks the FN 509 high for its performance.

At the range, the FN barrel did its magic. However, there were loads that the 509 clearly didn't like. That isn't unusual and should be kept in mind when selecting everyday carry (EDC) ammunition. Get to the range and try different loads.

FN's MHS version of the 509 was not selected as the new military sidearm, though the sample I tested certainly delivered the accuracy specs the Army was seeking. Still, it was announced on April 25, 2017, that Brink's, a leading provider of security solutions, had adopted the 509 for its armed guards. G&A's conclusion is that the FN 509 is a worthy contender for the civilian striker-fired pistol market.

FN 509

  • Type: Striker fired, semiautomatic
  • Cartridge: 9mm
  • Capacity: 17+1 rds.
  • Barrel: 4 in.
  • Overall Length: 7.34 in.
  • Height: 5.56 in.
  • Materials: Stainless steel, polymer
  • Weight: 1 lb., 11 oz.
  • Grips: Multi-textured, molded; interchangeable backstraps
  • Sights: Three-dot night sights
  • Trigger: 6 lbs. (tested)
  • Price: $650
  • Manufacturer: FN, 703-288-4507; fnamerica.com

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