FN 509 Optic Plate

Mounting a red dot on your FN 509 should be simple, secure, and repeatable. This optic plate is CNC-machined for a precise fit, finished for durability, and built around the footprints shooters actually use. Pick your optic, match the footprint, and you’re ready to install with hardware that stays tight and a profile that plays nice with co-witness sights.

Why this plate works

• Purpose-built for FN 509 optics-ready slides with proper geometry for reliable lockup

• CNC 6061 aluminum for strength without bulk; hard-anodized to resist wear

• Stainless hardware + locating pins for recoil control and repeatable zero

• Low, clean profile to support co-witness with suppressor-height irons

• Clear footprint options so you mount the right dot the first time

Compatibility guide

• RMR footprint: Trijicon RMR/SRO/RCR, Holosun 407C/507C/507Comp/508T

• 509T clamp-style: Holosun 509T (uses its dedicated plate style)

• ACRO pattern: Aimpoint ACRO, Steiner MPS

• Tip: Always match pistol cut → plate → optic footprint → screw length/torque

What’s included

• Plate, optic-to-plate screws, plate-to-slide screws

• Locating pins (where required)

• Quick setup card with best-practice torque steps

Install notes

• Degrease threads, then use blue threadlocker

• Torque to the optic and plate manufacturer specs

• Re-check torque after 24 hours and confirm zero at the range

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FAQ

Which red dots fit this FN 509 plate?
Choose the plate that matches your optic’s footprint. RMR pattern covers RMR/SRO/RCR and Holosun 407C/507C/507Comp/508T. ACRO plates fit Aimpoint ACRO and Steiner MPS. Holosun 509T uses its own clamp-style plate.

Will this help me co-witness irons?
Yes, the plate sits low to work with suppressor-height sights for lower-1/3 or near-absolute co-witness, depending on your optic body and sight height.

Do I need a sealing plate for an RMR?
Follow the optic maker’s guidance. Many users add a thin sealing plate to improve environmental sealing under open-emitter dots.

What torque should I use on the screws?
Use the exact numbers from your optic and plate manufacturers. As a general habit, clean threads, apply blue threadlocker, and tighten with a calibrated inch-pound driver.

My optic won’t hold zero—what should I check?
Confirm correct screw length (not bottoming out), use the supplied pins, verify torque after cure time, and make sure the plate and slide pockets are clean and oil-free.

Does this plate also fit FN 510 or FN 545?
Some share the V4-style interface; verify the cut on your slide and select the matching plate before ordering.