FN 509 Midsize 9mm pistol
Dan Z for TTAG
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FN America took their line of striker-fired pistols in a new direction in 2017 with the introduction of the FN 509. It was born out of their entry in the Army’s modular handgun system competition. They said at the time that the 509 had more than 1 million rounds to ensure that their new flagship 9mm pistol was reliable.

We’ve seen no reason at all to doubt it. Both the original full-size 509 (our review here) and the subsequently-introduced 509 Tactical model performed absolutely flawlessly in our testing.

FN 509 Midsize 9mm pistol
Dan Z for TTAG

All of which is a long way of saying that if you want a good evaluation of the FN 509 Midsize 9mm pistol, read our reviews of the original full-size and tactical models of the gun. Everything we’ve had to say about the previous models goes for the new FN 509 Midsize.

The big difference: about .36 of an inch. That’s the amount FN chopped off of the FN Midsize’s handle. It may not sound like much, but it makes a significant difference in your ability to conceal the gun. Both the Midsize and the big boy models have the same stainless steel four-inch barrel length, same sight radius.

FN 509 Midsize 9mm gun review
Dan Z for TTAG

Rather than a plastic clamshell box, the more compact pistol comes in a nicely embroidered zippered soft case. FN throws in a second flatter backstrap for small-handed shooters like me along with two 15-round magazines. Be forewarned, you’ll need a long punch to change it out yourself. It’s a PITA, but a minor gripe as you’ll only have to do this once.

FN 509 Midsize 9mm pistol
Dan Z for TTAG

The 509 Midsize has bevels cut in at the bottom of its multi-surfaced grip to help you yank out a magazine should one fail to eject. That never happened to us, but it’s definite a plus.

Like the earlier models, the Midsize’s grip is a cavalcade of textures; pyramidal nubs on the sides, angled “tabs” on the front and back and skateboard tape-like surfaces on the areas above where your thumb naturally falls.

Some have complained about this in terms of aesthetics, but as a practical matter, it work very well. Your hold on the gun will be sure and firm (even with a wet hand) without the texture being too aggressive.

FN 509 Midsize 9mm pistol
Dan Z for TTAG

Like their FNS pistols, the 509s have an elongated magazine release button. Unlike those earlier models, the 509’s buttons are more textured and stand a little more proud of the grip, resting in contoured “pocket.” That pocket has been re-shaped slightly (it’s a little larger) from that of the full-size gun, making for easier activation by small-handed shooters without changing their grip.

Sure to please lefties, the 509 Midsized is full ambidextrous right out of the box. There are slide stop levers on the left and right sides and you won’t have to switch the magazine release.

The 509’s stock trigger is very good. It breaks cleanly at 5.4 lbs and has a very tactile, audible reset. Controlled rapid fire and double-taps are not an issue. FN says the 509 Midsize trigger shoe has a flatter face than earlier models making for a better, more controlled trigger press. Jeremy wasn’t in love with the earlier version on the Tactical model. This one is near-ideal.

FN 509 Midsize 9mm pistol
Dan Z for TTAG

Takedown is as simple as a striker-fired gun should be. Check that the pistol is clear and safe. Then lock the slide back, drop the take-down lever, release the slide forward, then pull the trigger. The slide comes right off.

That captured recoil spring on the 509 Midsize is the same one FN included in the 509 Tactical model. With its cocking serrations fore and aft, the lighter spring makes the 509 Midsize easier to rack, but the pistol still performed flawlessly with a variety of ammo weights we tested.

FN 509 Midsize 9mm pistol
Dan Z for TTAG

The 509 Midsize has drift-adjustable, glow-in-the-dark three-dot luminescent sights (tritium night sights are available). The front of the rear sight is vertical, so you can use it to rack the matte black slide one-handed on a belt or hard surface if the need arises. And we hope it doesn’t.

FN 509 Midsize 9mm pistol
Dan Z for TTAG

We tested the new Midsize with a range of range ammo from Armscor (115 and 147 grain), Winchester and Remington. Personal defense ammo tested included Federal HST and Remington HTP.

Braced groups at 25 yards ranged from 4.15 (Federal HST) to just over 5.5 inches (Winchester white box). Those are very respectable results that indicate — as if there were any doubt — that the 509 Midsize is more than accurate enough at personal defense distances, either while carried or in a home defense role.

The 509 Midsize will, of course, most often be compared to the GLOCK 19 Gen5 which is also an excellent gun. The FN costs anywhere from $25 to $60 less, has better ergonomics and a better trigger. Then again, the 509 has fewer aftermarket choices, though there are more available all the time. You owe it to yourself to shoot both.


armscor ammunition

Specifications: FN 509 Midsize Pistol

Caliber: 9mm
Operation: Double-action
Magazine Capacity: 10 or 15 Rd (higher capacity mags can be used with a grip sleeve)
Weight: 26.5 oz.
Barrel Length: 4.0″ cold hammer forged
Overall Length: 7.4″
Height: 5.2″
Width: 1.35″
Trigger Pull: 5.5 – 7.5 lb.
MSRP: $649 (about $549 retail)

Ratings (out of five stars):

Aesthetics: * * * *
Is it beautiful? No 9mm striker-fired pistol is beautiful. But it definitely isn’t ugly in the way some are. The 509 Midsize has a certain industrial style to it.

Reliability: * * * * *
Pefect. Nothing else to say.

Ergonomics: * * * * *
The 509 Midsize does every little thing right. It’s fully ambidextrous to accommodate lefty shooters. The texturing is an effective mix of just the right patterns in just the right places. The mag release and replaceable slim backstrap mean even those of us with small hands can reach all the controls. The external extractor acts as a loaded chamber indicator. If only every pistol maker put this much thought into their designs.

Customization: * * *
As good as FN pistols are and always have been, they’re not up there in sales volume with the GLOCKs, Smith & Wessons, SIG Sauers and Rugers of the world. That’s a shame, because they consistently match or beat the other big gun makers’ products. That means, however, that there are fewer options out there for holsters, sights, replacement triggers, etc. Which isn’t to say there are none. You can find everything you need and there are more offered all the time.

Overall: * * * * *
The 509 Midsize is an excellent 9mm pistol. It’s almost the Goldilocks of gun sizes…just right for almost any job short of pocket carry. If you’re going to own one handgun — for carry, for home-defense, for competition, for fun — there are a lot of good arguments for making this that gun.

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  1. I absolutely hated my full sized 509. I looked for any excuse possible to trade it in for something better. 11,000 rounds later, I stopped looking. The thing is great. Well made and a pleasure to shoot. I guess it needed a little break-in period. I would not get rid of the thing and highly recommend it to anyone looking for a quality pistol.

  2. I’ll stick with my hammer fired FNP-45. Totally reliable, 15round mags, and weighs only 50lbs loaded. Yeah, I lean to the side a lot.

  3. I love my 509M with one exception. The sights. I did not get the night sights, and the luminescent sights always seems to be too dark unless they were “charged” significantly. Easy fix though. I swapped them out for some Sig X-Ray sights, and couldn’t be happier.

  4. “The external extractor acts as a loaded chamber indicator.”
    how so? by being flush unloaded and protruding slightly when chambered?

  5. I didn’t care for the 509. The mag release was a pain due to the other side being pushed out and into my finger. Had to change my grip just to swap mags. And the slide lock was definitely harder on the left side as opposed to the right.

    • Yeah, I’m right handed and had to adjust my entire hand to drop a mag. I liked the 509 but never carried mine due to this. I’ve switched to other pistols that I can swap mags quickly in case I ever have a need. I didn’t have a problem with the FNS9c and if it wasn’t for Sig365 taking 10 round mags I’d own another FNS9C.

    • Glad to hear I’m not the only one. I had the same issue with the FNs, specifically the FNS-9C. I really wanted to like it and after much research had it penciled-in to be my next carry gun, but after two minutes of handling it I knew it wouldn’t work. That ambi mag release just wasn’t natural. The harder I pushed with my thumb, the harder the opposite side pushed into my palm., cancelling it out. I had to completely adjust my grip in an awkward way to eject the magazine.

  6. I like the texturing on this pistol. Looks better balanced than the bigger one.

    Never been a fan of hinged triggers.

    Maybe one of my friends will buy one and let me try it……for a month or two😁.

  7. Pretty Glocky. Its Glockyness appears pretty well done, without any major misGlockysteps.

    Still not the real thing, but after 39 years they are getting better at it.

    • Maybe I’m missing something…
      It’s heavier than a G19.
      It’s bigger in basically every dimension than a G19.
      It has 5 rounds less capacity in standard form.
      Costs about the same as a G19.

      I’d say it needs more Glockiness.

  8. There are so many wonderful pistols being made I have no idea how you could select the best one for your needs. I went through this about a year ago and was sure I had my first striker fired plastic framed triggered trigger picked out but bought another full size hammer fired alloy frame 9mm this time in single action only. The same model I bought twice before, still own them all and have been using since 1983. Why? The brand has been reliable, durable and I can hit what I am shooting without retraining. Saved a fortune in magazines and I am at peace when I carry this piece. My point is the first marketing genius who can get his pistol into the hands of the shopper wins. Had I been able to shoot an FN or Walther or HK without going on a pilgrimage I might have fallen in love all over again.

  9. I didn’t see “+P” anywhere in the review. Is that a given? Did I read it too fast and overlook it? I can’t imagine a new 9 being introduced that isn’t.

    • It’s a personal flaw that I fully acknowledge is irrational, but I despise Belgium. It is like someone picked the worst attributes of other European societies and combined them into one obnoxious, irritating country. If France got too high at a concert and hooked up with Germany in the bathroom, the unwanted bastard offspring would be Belgium.

      • Historically, that’s actually kind of what Belgium is. It was cobbled together out of pieces of France, Germany, and the Netherlands after WWI. A country created by modernists out of political expediency and postwar ennui. No national identity, no cultural raison d’etre. The perfect headquarters for the EU.

  10. The FN 509 series has intrigued me since they came out. I think they look cool if not industrial looking. But they are nothing I don’t basically already have (XD mod 2 9mm in 4″ and 5″) so I haven’t pulled the trigger on one, so to speak.

    • Same here. I *love* the way they feel in my hand, though. If they’d been around back when I was buying my pistol, I’d probably have bought one instead of the XDm.

  11. Put one of these in your hand, then pick up a G19…then buy this. Unless you foresee operating operationally in watery environments…then buy a Glock. These choke on water.

  12. Took me a while to pull the trigger (no pun intended lol) but I finally bought it and I love my fn509. I confess, after seeing Hickocs review I bought it. So far I put over 500 rounds through this gun no problem, both fmj and jhp. My brother who has several guns, was also so impressed by it’s performance at the range that he went and bought one too. I almost bought the czp10, I liked everything about it and if it weren’t for the difficult mag release I would’ve bought it. CZ if you are reading this and you haven’t done so, please fix that. I hope my review helps someone make a decision.


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