I have purchased and tested many optics in the past few years, and I feel confident to recommend the best FN 509 red dot sight on this guide based on their ability to retain zero and being durable.

Best FN 509 Red Dot Sights

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  • Best Overall
  • Largest Field Of View
  • Best For The Money
  • Best Lens Durability
  • Best For Range
  • Full Weatherproof

Trijicon SRO - Largest FOV

red dot for fn 509 tactical

The Trijicon SRO is by far the best large window optic for the FN 509 tactical, FN 509 LS Edge, and other handguns for fast target acquisition.

fn509 trijicon sro pov in action

When shooting the gun, I rarely lost the dot within the window because its so large even when I was slightly off center. The dot always appears back to the center.

Easier Battery Access - Another feature I love is the ability to load the battery right from the top! No sight removal or re-zero required compared to the original RMR

trijicon sro vs rmr window size front

Better Follow Up - I can effortlessly reacquire the red dot sight after follow-up each shot and get right back on target

Same RMR mounting footprint - Use the existing RMR mount without having to buy special accessories.


  • Magnification: 1X
  • Reticle: 5 MOA option is the best
  • Turret Value: 1 MOA / Click
  • Field of View: Round 0.98" X 0.89"
  • Construction: 7075 T6 aluminum
  • Dimension: 2.2"X1.3"X1.4"
  • Weight: 1.6 oz
  • Battery Life: 3 - 4 years

Read Trijicon SRO Review

Holosun 507C X2 - Best Overall

fn 509 red dot sight

The Holosun 507C X2 does the same thing the original V2 model does but better in every way that improved the shooting experience while still remains affordable.

32 moa ring only 507c

Surprisingly the 32 MOA ring reticle actually appears much crisp without the center dot for astigmatism. It works well for hitting IPSC size targets up close.

fn 509 optics

NEW ACSS Model - Watch the 250 MOA outer ring guides the eye back to the reticle center

Uses RMR Footprint - No special adapter or milling required! Just use the same Trijicon RMR adaptor plate that comes with the FN 509 Tactical.

Bigger Buttons - The adjustment buttons aren't too small or too big for my hands, but they do have tactical button texture to adjust even for users with big fingers

holosun 507c x2 battery tray access 2

Near Infinite Battery life - 50,000 hours of battery life plus solar panel backup power if the battery goes out.

Side Loading Battery - This feature eliminates the need to remove the sight for battery swap and re-zeroing. Access the battery from the side tray

fn509 ls edge with holosun 507c x2

Solar Power BackUp - Solar fail-safe power kicks in immediately when the battery dies, so the optic will always remain on and ready.

At this price point, which is the lowest it's ever been for a Trijicon RMR alike sight, You'll save a ton of money. Just make sure to click the button below for the best deal.


  • Magnification: 1X
  • Reticle: 1 MOA, 32 MOA ring, or combined
  • Turret Value: 1 MOA / Click
  • Field of View: 0.63" X 0.91"
  • Construction: 7075 T6 aluminum IP67 rated
  • Dimension: 1.78"X1.15"X1.15"
  • Weight: 1.5 oz
  • Battery Life: 3 - 4 years

Read Holosun 507C X2 Review

Trijicon RMR - Best Durability

what red dots fit fn 509 tactical

Trijicon RMR RM07-C-700679

Trijicon RMR is the grandfather of all modern red dot sights for pistols. This is one of the most durable red dot sights made ever for duty use on your FN 509 tactical pistol.

LED RMR reticles

Tighter Battery Grip - The Type 2 model grips the CR2032 battery much tighter to prevent lose electrical contact during high G recoil

Combat Proven Durability - The forged 7075 T6 aluminum frame and body features rounded hood edges divert any point impact stress away from the glass to withstand physical abuse

fn 509 rmr

Rounder Dot Appearance - 6.5 MOA red dot that gives that big center reticle without the red dot dots looking smeared when dealing with emitter glare

Slide Racking Assist - RMR is very rugged for slide racking against any hard surfaces. 


  • Magnification: 1X
  • Objective Lens: 0.9" x 0.6"
  • Eye Relief: Unlimited
  • Reticle Type: 6.5 MOA dot
  • Turret : 1 MOA / Click
  • Length: 1.8 inches
  • Weight: 1.2 oz
  • Battery: CR2032
  • Battery Life: 4 years 

Leupold DeltaPoint Pro - Large FOV Like SRO

fn 509 red dot

The DeltaPoint Pro is Leupold's best open emitter red dot sight. After shooting this one side by side with the Trijicon SRO, the field of view is as much as a Trijicon SRO but in a rectangular shape. In addition, the DeltaPoint Pro does sit a bit taller on the slide.

deltapoint pro unboxing 2

Everything you need to install the optic is included in the box. The FN 509 comes with an factory adapter plate and spacer to fit the DeltaPoint pro right out of the box as well.

Larger Window Than RMR - The field of view is so much bigger than Trijicon RMR, and the optic height is just right for most shooters

deltapoint pro on fn 509 ls edge top view

6 MOA and 2.5 MOA - In my experience, the 6 MOA option is much easier to see and it's a feature now available for shooters with astigmatism

Extra Lens Hood Protection - The added lens hood protects the optic from receiving direct impact that increases durability and making it fail proof.  

leupold deltapoint pro top view

Easier Battery Access - No sight removal or re-zero required. This user friendly design feature has been well tested and implemented into many other new optics today.


  • Magnification: 1X
  • Objective Lens: 1.01" x 0.68"
  • Eye Relief: Unlimited
  • Reticle Type: 2.5 or 6.5 MOA
  • Turret : 1 MOA / Click
  • Dimension: 1.8" X 1.3" X 1.3"
  • Weight: 1.9 oz
  • Battery: CR2032
  • Battery Life: 1600 hours

Read more DeltaPoint Pro review

Vortex Venom - Best Value

fn 509 red dot

The Vortex Venom is an entry level red dot sight. It's not for duty use, but it's good for range use without spending over $300. Personally, I think the sight is very compact and the lens frame is so thin that there is barely any sight picture obstruction. However, for duty use, I wouldn't recommend this optic except for range use.

vortex venom on FN 509 ls edge slide

Top-Loading Battery Access - Install the battery right from the top without the worry of removing the whole sight or having to re-zero the sight afterward

Multiple Intensity Settings - Rapid target engagement under a full range of lighting conditions

vortex venom battery access

Wide Field of View - The thin lens hood frame doesn't obscure the brightness of the dot in the shooter's field of view for better sight acquisition and does not lose the brightness and accuracy of the dot.

Super Lightweight - The entire optic only weighs 1.1 oz built with rugged aluminum housing, its compact design helps for high speed shooting

vortex venom front view on fn 509


  • Magnification: 1X
  • Window Size: 0.58" x 0.77"
  • Eye Relief: Unlimited
  • Reticle Type: 3 or 6 MOA
  • Turret : 1 MOA / Click
  • Dimension: 1.6" X 0.98" X 0.95"
  • Weight: 1.0 oz
  • Battery: CR2032
  • Battery Life: 3000 hours

Read Venom Review

Common FAQ

FN 509 Tactical Red Dot Compatibility

fn 509 tactical red dot compatibility

The FN Low Profile Optics Mounting System is compatible with almost all micro red dot sights on the market.

The included package contains mounting plates and screws for some of the most popular optics such as:

  • Vortex Viper, Razor, Venom
  • Docter Optic
  • Trijicon RMR, SRO
  • C-More STS2
  • Burris
  • Leupold DeltaPoint Pro

Highly recommend using the aftermarket CHPWS plates for tighter slide to plate contact surfaces.