FN 509 Midsize Review: First Impressions

The gun industry and all of our audience usually fight between a few different firearm manufacturers. I won't name any names this time around because this 509 Midsize review isn't about them.

You and I both know who they are, and that's fine. I'm here to tell you that this gun, and this firearm manufacturer deserves a seat at the top. The FN 509 Midsize is a serious contender for the best striker fired 9mm gun in existence, and I have no problem saying that.

Up close of trigger side.

Fn 509 Midsize Trigger —

To me, it all starts with the trigger of any gun I'm manipulating.

In a world where accuracy is directly related to proper trigger manipulation, the 509's trigger wall offers an excellent, solid stop after an initial .25-.50 inch or so of take up. And, after that take up, there is a wall, or that solid stop, that you must overcome to fire the pistol.

The trigger then breaks with a certain crispness not found on many striker fired guns. Also worth noting about the trigger, which is a feature I love on most of FN's pistols, is a nice, wide, flatter trigger shoe.

It helps me have positive identification that my finger is in the right spot and helps even the pressure of the trigger press out across a bigger area.

FN 509 Midsize Ergonomics —

This FN 509 Midsize feels great in hand, even for my massive man mitt hands, though it does come with an extra backstrap insert if you need to adjust the size at all for smaller hands.

Here is the larger of the backstraps installed, which is how it came.

The 509 M has ambidextrous controls to include the mag release as well as the slide stop lever. The Midsize version of FN's 509 is a little different in these ergonomics than the Original version is.

FN corrected a few things people took issue with, which are highlighted in this video we filmed while out at SHOT Show, 2019:

One thing I'm not a fan of on any gun, and I know I'm strange here, is a too aggressive grip. This 509 Midsize grip is a little too aggressive for me.

Grip front

Here is another view of the grip, where I used the macro setting on my camera to really try to show it off. Again, I know I'm a rarity in the gun industry, and most folks prefer an aggressive grip, which is why it's there to begin with.

Up close grip

Something that I wish gun manufacturers would catch on to, is slide serration effectiveness. Too often in this industry, slide serrations suck. Seriously.

They're either non existent or too existent. Rarely do gun manufacturers offer both front and rear slide serrations that do what they're supposed to do, effectively.

The 509 Midsize's serrations offer the perfect amount of grip while not being too grippy, or worse, sharp.

Here I'm trying to show the slide serrations. Also notice the rail for attaching whatever you'd like that'll fit.

I personally don't struggle with racking the slide on any gun I've ever handled (minus the Auto Mag before I knew how to do it properly), but I'm not most people. I'm 6'4″ and 300+ pounds. My hands are massive and I'm not exactly weak. But, some people are and some people rely heavily on slide serrations.

The Fn 509 M gets it right, and I hope other companies pay attention.

FN 509 Mid at the Range —

So far I've got a few hundred rounds downrange with it, including 135 grain Hydra Shok JHP, 115 grain Federal American Eagle, 115 grain reloads, and a few others.

It runs like a champ and only had a couple light strikes on the reloaded ammo which was notorious among the other guns I shot it with as well. 

Other than that the 509 Midsize performed exactly as expected: Flawless.

I always feel like I should do a video of me shooting each gun I do a review on. Sometimes it's not feasible, especially when I suck at recording video. But I sneaked this little vid of me shooting the 509 Midsize one handed in. I pulled it from our Facebook page.

Here I am, holding the camera with one hand, and shooting the gun with the other hand. At the time this was filmed I had only about 50 rounds of ammo through the 509. It was still very much a new gun to me.

Though, be it far from me to make excuses for my misses.

I do want to take a moment and say that canting the firearm slightly while shooting one handed is something instructors teach. I've requested one of our instructors write up an article on it, so stay tuned.

I'm not a gangsta out of Chicago as some on our Facebook page have said. Shooting one handed like this helps mitigate recoil. Not to mention that my sights actually line up more naturally for me than if I were to hold it straight up and down.

FN 509 Midsize Carry —

I've been using a Clinger No Print Wonder V3 to carry this 9mm pistol, which does help it disappear quite well. I've got a review coming your way on this holster, so stay tuned for that.

Here it is resting on the V3.

The idea behind the 509 Midsize is to offer a bigger gun with decent 15 round capacity that will actually conceal better than the Original 509 does. As a point of transparency I've never carried the Original 509, so I can't compare it in that respect.

What I can say, however, is that it conceals about as well as any gun with a 4 inch barrel and an overall length of 7.4″ does. As a point of reference, it's just slightly (and I mean slightly) bigger than the main competition.

FN 509 Midsize Sights —

Rear sight

The sights are standard 3-dot sights. They're the luminescent ones that glow in the dark. I have found that the “glow” retires quickly and needs to be recharged fairly often in low-light use.

There is an option for upgrade to true night sights, however, so if that's important for you make sure you check that option.

Sight Alignment

For day time shooting, they were sufficient and the front sight offers a big dot that's easy to see.

The rear sight enables racking the slide one handed if your support hand gets wounded.

Notice the rear sight.

FN 509 Takedown —

The takedown of this pistol is much what you'd expect from any striker fired pistol these days. Simply remove the magazine, visually inspect that the chamber is empty, lock the slide to the open position, pivot the takedown lever downward, send the slide forward, and pull the trigger.

The slide will come off and you can then remove the barrel and recoil spring to get the following result to clean your gun:

Field Stripped

I've read that the internals are the same as the Original 509, though I have not compared them to each other.


509 Midsize vs FNS9-C —

Something I was asked early on by a few people who know I carry an FNs9-C on a near daily basis, is how the 509 Midsize compares to it. I'd say that it's very similar in some manners, but different in others.

Clearly the 9-C is smaller, but the triggers are similar. I'd also say that the serrations are better on the 509 M, while I prefer the grip texture on the 9-C more. Overall, it's close and I really like both of them.

Notice the bevel at the bottom of the grip? I have not verified, but believe that's to aid in magazine stripping.

Another thing that I like more about the 509 Midsize when comparing it to my FNs9-C is the magazine release. It's more pronounced, sticks out a bit more, and is just overall easier for me to hit.

While I am admittedly still getting used to the difference, I don't have to change my grip as much on the 509. So it's clearly a winner in that regard.

Here they are, opposed each other.

I will say that I've got a few thousand rounds through my FNs9-C without malfunction and only a handful of cleanings. I refuse to own a firearm that requires to be clean in order to function properly. I've found that keeping it lubed (that link goes to the lube I use, by the way, and the applicator is brilliant) is sufficient for correct operation, and the 509 seems to be similar in that regard.

Minus the original out of the box cleaning when I first got it, I have not cleaned it since. It still works flawlessly after a few hundred rounds. I'll update you again, after I shoot it 700 more times.

SPECS pulled from FN's Website

  • CALIBER: 9mm
  • OPERATION: Double-action
  • MAG CAPACITY: 10 or 15 Rd.
  • WEIGHT: 26.5 oz.
  • TWIST RATE: 1:10″ RH
  • HEIGHT: 5.2″
  • WIDTH: 1.35″
  • TRIGGER PULL: 5.5 – 7.5 lb.
  • SIGHT RADIUS: 5.79″

Conclusion —

So far the FN 509 Midsize is the contender for the title I thought it'd be. At this point, I've had zero malfunctions (only ammo related ones) on only the initial out of the box cleaning with a few hundred rounds through it. It feels great in hand, and the controls work well. I'll continue to update this gun review with more findings as I shoot it more.

This gun is available with an MSRP of $649, and can likely be found under $600 in many areas.

It's a clear winner in my eyes.

More Pictures —

Inside slide

Left Side


Up close of serrations and rear sight

About Joshua Gillem

Josh is a lifelong practitioner and student of the gun. He grew up shooting/hunting with his dad, and was given his first gun, a 12 gauge shotgun, when just a small boy. After high school, he joined the Marines where his love for firearms blossomed as he qualified with an M16A2, an M9, and a 240G. Josh has been writing about firearms and tactics for several years, owns the blog Gunners Den, is a staunch supporter of the Second Amendment, and believes that each individual person has the right to self-defense by any means necessary. Currently residing in gun-friendly NC, he carries a concealed gun on a daily basis, even in his own house.


  1. leonard jindra on April 2, 2019 at 7:57 am

    I believe this `pistol is very similar in style and function except for the long barrel to my 9mm s&w shield which can now be purchased for a msrp of $320.00 which is quit a bit cheaper than the 509!

    • Kenneth on July 30, 2019 at 9:59 pm

      The only thing similar is that they are both polymer, striker-fired 9mm pistols. The Shield is much smaller in every dimension, and holds 7 or 8 rounds, compared to 15 for the FN 509 Midsize. It is going to be much more comfortable to shoot the larger, heavier gun compared to a subcompact. There’s really no comparison.

  2. Steven on April 2, 2019 at 7:59 am

    Nice firearm but it don’t beat my P 320 ?

    • Gary Avrett on December 19, 2019 at 8:59 pm

      I love my P320 X Carry 9mm. Best I have owned. Better than my M&P M2.0 9mm. An Apex trigger upgrade made the M&P M2.0 9mm much better but for some reason I am more accurate with the P320. I tried an Apex trigger in the P320 and went back to the stock flat trigger. Haven’t had any experience with curved triggers in the P320 though.
      Anyway there are two guns I would be very interested in trying. An FN509 9mm and Walter PPQ 9mm or .45 ACP.

  3. THOMAS on April 3, 2019 at 10:04 pm

    Yes Steven yes it does ….it beats it in every way …. your on the sac of the sig in see now where are the Glock douches or my Cz brothers??

    • Thomas Fleming on July 17, 2019 at 1:59 pm

      Is the 509 midsize available in Massachusetts yet?

      • Mike Misslin on November 29, 2019 at 5:20 pm

        Yes. Most gunshops have them.

    • dean on July 20, 2019 at 9:13 am

      Care to state how , sig p320 comes with many of the same attributes out of the box , serrations,night sights, etc.. , have you fired both curious ?

  4. Marcus on April 3, 2019 at 10:36 pm

    Would love to know how it compares with the VP9sk. I don’t own either, but have been considering the VP9sk. Sounds like player two entered the game.

  5. Scotty B on August 23, 2019 at 12:16 pm

    Everyone in the business is looking for their G19 killer, or at least an alternative to take away from that market.

    The M&P 9c 2.0 is a really great gun, more ergonomic, better sights, and equally reliable.

    The Sig 320 is also an awesome shooting piece, though thicker with a much higher bore axis, some love some hate. I own an X5 and the trigger is very nice, but not special.

    The Walter P99c is also a phenomenal option, underrated fore sure. Ultra reliable and comfortable. I own the full size and it is my favorite stock 9mm for sure.

    Everyone has their favorite option for sure.

    All that said, i have just ordered the 509 mid size because, as the owner of another FN pistol, I know how excellent their quality is. The 509 is being hailed by nearly every pro reviewer as possibly the best compact 9 ever made and I have to find out for myself.

  6. Tim on December 19, 2019 at 7:40 pm

    I do have a 509 and I have to say it is really a fine firearm and the trigger and sights are great. I have never had no kind of failure with this pistol. I carry it everyday.

  7. Rudolph Marchand on February 15, 2020 at 2:16 pm

    glocks suck

  8. Dan on March 11, 2020 at 12:03 pm

    I have both the Sig p320 and the FN 509, My Sig was definitely my favored gun until spending a few range days with the 509, now it seems to be a disappointment on accuracy and ease of use, but I’m a lefty and that could play into that feeling, The 509 is much easier to handle, load, release, fire than the 320, it shoot’s tight groups almost effortlessly at 25 yards and closer, zero malfunctions, just a pleasure to carry and fire.

    It is now my go to carry gun, and really pushing some of my more accurate range guns, almost seems to be the best of both worlds. ( especially for a lefty ) my .02 cents.

  9. Thomas C on May 7, 2020 at 3:29 pm

    I actually have an offer of one these right now for my CZ P-10c. I’ve upgraded the trigger and sights on the CZ and I have 5 mags would be trading down in price but curious what the general consensus was regarding a FN 509M vs a P-10c?

    Of all the newer poly striker the only one that has bumped out my G-19.5 & G26 was the IWI Masada. I REALLY love that gun. Hand feel is utterly subjective but the Masada just feels right in my hand. Better capacity than my Glocks but thinner and carries better IMO, optic ready, actually like the grip pattern, really good trigger (Best stock trigger I’ve fired and I am trigger Snob). It also is modular like the Sig 320. I’ve seen them as low as $385 now. The stock sights were mediocre but I popped a Holosun RMR on the day I bought mine and it is tack driver out to 25. Hands down best bang for your buck in the space below $400 with almost all the features of a G45 MOS and P320. Done with my Masada love fest but more people should shoot that Israeli gem.

    Now I really think I am going to pull the trigger on the 509 deal so I can see if I like this better than the Masada that is my only EDC now and may end up putting the G21 in the safe and be my nightstand gun too…. Unless I really love the 509.

  10. Scott on July 3, 2020 at 7:32 pm

    I own three FNS 9s and two 509s. My daily carry is a509 mrd with aTrijicon rmr, and sometimes a Sig p365.FN makes a great (underrated) firearm and while there are many good polymer guns out there I feel in my opinion FNs are the best all around polymer gun on the market with the CZ P10 a really close 2nd.

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