Best FN 509 Parts & Accessories for 2026 (Upgrades That Matter)

The FN 509 grew out of FN’s U.S. Army handgun trials and became a rugged, reliable striker-fired duty pistol with a well-earned reputation for durability and a great grip. Its aftermarket is more curated than a Glock’s, so an FN 509 build is about the essentials: a cleaner trigger, better sights, a red dot on the optics-ready models, a light, and plenty of magazines. A few well-chosen parts sharpen an already-serious duty gun.

Below are the FN 509 parts and accessories we would add first. These fit the full-size and Midsize FN 509 in 9mm (confirm your exact model, the Tactical, LS Edge, and Compact differ in a few parts), and each pick is backed by a live price check across the retailers we track.

Table of Contents

FN 509 Upgrades at a Glance

Category	Our Pick	Why It Makes the List
Trigger	Apex Action Enhancement	A lighter, crisper pull than the factory trigger
Night sights	Trijicon	Bright tritium that holds zero
Red dot optic	Holosun 507C	Fast aiming on the optics-ready 509 MRD/OR
Weapon light	Streamlight TLR-7	Slim 500-lumen light for the full-size rail
Magazine	FN factory 17-round	Reliable full capacity, straight from FN
Extended magazine	FN 24-round	Big capacity for range or home defense
Holster	Molded Kydex	Duty or carry retention with a clean draw

Best Trigger: Apex Action Enhancement

The FN 509’s factory trigger is serviceable but a bit heavy with a spongy reset. An Apex Tactical Action Enhancement Trigger cleans up the take-up, lightens the pull, and gives you a crisper break and a more tactile reset while keeping the gun’s safeties intact. It is the single upgrade that most changes how the 509 shoots and an easy at-home install.

Best Night Sights: Trijicon

Upgrading to a proper tritium set gives you a fast front-sight focus in daylight and a glowing aiming point at night. Trijicon’s night sights for the FN 509 are bright, durable, and hold zero, and they come in suppressor and optic co-witness heights so they still work if you add a red dot. It is a cheap upgrade that pays off every time the light gets low.

Best Red Dot Optic: Holosun 507C

If you have an optics-ready 509, the MRD, OR, or LS Edge, a red dot is the biggest hit-probability upgrade you can make. The Holosun 507C is the value benchmark: a rugged open reflex with shake-awake, a multi-reticle system, a solar backup, and years of battery life. FN’s optics system uses adapter plates, so confirm the correct plate for your dot, and co-witness with suppressor-height sights.

Best Weapon Light: Streamlight TLR-7

A duty or home-defense 509 needs a light. The full-size frame runs a proper rail, and the Streamlight TLR-7 is the slim-body standard at 500 lumens, with a compact head that clears most holsters and ambidextrous switching. Buy a holster molded for a light-bearing 509 once you mount it.

Best Magazine: FN Factory 17-Round

Genuine FN magazines are the reliable standard for the 509, and you should own several. The full-size and Midsize guns run 17-round magazines, and FN’s build quality means they simply work. Stock up, magazines are the cheapest insurance you can keep in a range bag or on a duty belt.

Best Extended Magazine: FN 24-Round

Want more rounds on tap for the range or home defense? FN’s factory 24-round extended magazine is the way to do it, the same reliable FN quality in a higher-capacity stick. It is a favorite for a nightstand 509 or a range gun, and it drops right in.

Best Holster: Molded Kydex

Whatever role your 509 plays, the right holster makes it work. A molded Kydex holster made for the FN 509 gives you secure retention and a clean, consistent draw, in OWB for duty and range or IWB for concealment. Match it to your exact configuration, bare gun, light-bearing, or optics-cut, because a universal holster is a compromise you will feel every time you draw.

How to Prioritize Your FN 509 Build

The FN 509 is a rugged duty gun, so upgrade in the order that sharpens it:

1. Night sights first. Cheap, easy, and they work when the light is bad.
2. A red dot if you have an optics-ready model, the biggest hit-probability gain.
3. A light and a trigger for a defensive role and a cleaner break.
4. Plenty of magazines and a good holster to round out a duty or home-defense setup.

Want the background on the gun first? Read our FN 509 review, then see how it fits the field in our best full-size 9mm pistols roundup. Feed it with quality 9mm ammo.

Frequently Asked Questions