I Carry: FN America FN 509 Compact MRD Pistol with Swampfox Justice Red-Dot Sight

posted on February 5, 2021

Firearm: FN America FN509 Compact MRD (MSRP: $799)

The FN509 Compact MRD from FN America is an underappreciated gem of a concealed-carry option. With 12-round capacity, a slide cut for multiple optics using one of the better-designed plate systems and a host of carry-friendly touches, it’s somewhat surprising the FN509 Compact doesn’t pop up more frequently. A quick note, first: While FN refers to this pistol as a Compact, it really fits more into the subcompact category as discussed in our Spotlight on the subject – the grip requires a floorplate extension to accommodate all three fingers; with a flush floorplate, the pinkie finger of the strong hand will curl under the magazine. FN offers a Midsize version that fits into the designation typically thought of as Compact.

Regardless of nomenclature, the FN509 Compact MRD offers a lot to the concealed-carrier. Truly ambidextrous, only the takedown lever is not mirrored on the “southpaw” side – and the magazine release is an honest-to-goodness ambi, capable of being accessed on either side without needing to be swapped. Suppressor-height sights come standard in conjunction with the optics-mounting system and feature all-black front and rear sights with glare-reducing serrations. The grip is aggressive, with multiple textures all designed to improve purchase when shooting the small pistol. While magazine capacity is 12 rounds, the Compact can use the larger magazines from the compact, full size and tactical versions of the 509 – although the 24-round magazine that accompanies the Tactical FN 509 is probably best used as a back-up.

The MRD (mini-red-dot) system on the FN509 is a complicated matter of inserts, plates and o-rings. Coming out of the box, there’s an insert (FDE to match) that not only mates with the plate cover, but also the Leupold DeltaPoint/SIG Sauer Romeo mounting footprint. Other footprints are covered with a series of inserts and plastic plates that fit together on the top of the slide, and while it is somewhat confusing, FN does a pretty good job keeping everything straight in the manual. As long as you know the footprint of the optic you’re using, it should be pretty easy to set up. The benefit of this system, like the Glock MOS and the Smith & Wesson CORE, is it allows you to use a wide variety of pistol optics. You can use what you have already, or buy something later and still be able mount it to the 509 Compact MRD.

What the FN509 Compact MRD boils down to is a sturdy pistol that’s easy to conceal and easy to shoot. The MRD offers a wide variety of common red-dot optics compatibility, while the overall size even with a red-dot sight attached is still pretty small. It’s light, ambidextrous and solid – great characteristics in an EDC choice. 

Optic: Swampfox Justice (MSRP: $259)

Optics, especially those built to withstand the recoil forces associated with being mounted on a reciprocating pistol slide, often come with significant price tags. Offerings from Swampfox, however, are definitely on the more affordable side of things without sacrificing durability and optic clarity. The Justice red-dot sight we’ve put on the FN509 Compact offers a 3-MOA dot with 10 illumination levels. It features a 27 mm window, 1-year battery life on medium setting according to Swampfox and fits the RMR footprint.

Swampfox’s red-dot sights feature what the company calls “Shake ‘N Wake” motion-sensing technology to save battery life. After 5 minutes of inactivity the dot powers down, but the slightest movement will reactivate. Holding down the button to decrease brightness for 3 seconds will turn the unit off completely, and depressing the ”increase-brightness” button turns it back on. That’s about all there is to activation; the rest is standard red-dot stuff. We’ll be keeping an eye on the durability and longevity of this unit to see if it’s as robust as the Kingslayer we tested previously (spoiler alert: we’re pretty sure it will…) 

Holster: JM Custom Kydex AIWB (MSRP: $70 stock, $80 as configured)

We’ve featured holsters from JM Custom Kydex previously, and the company’s wide range of offerings and a la carte style ordering, combined with excellent fit-and-finish, make it a go-to staple. In the case of the FN509 Compact, the fit is really nothing short of amazing – precise, clean lines that match the pistol at every angle, combined with an optics cut that leaves plenty of room. Not only that, retention was spot-on from the get-go (although it can easily be increased or decreased if desired). Single-sheet Kydex construction makes for a sturdy holster that should last pretty much indefinitely.

In keeping with the modularity of the JM Custom Kydex offerings, we’ve configured this AIWB holster with three different parameters. The belt clip is the slim Discrete Carry Concepts (DCC) monoblock, the color is red and the aforementioned optics cut. The red color adds $5 to the price, as does the optics cut, but the monoblock is a standard substitution. The AIWB is available for right- and left-handed shooters, and a muzzle pad is an option for more comfort if desired.


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