Apex Optic Mount for Holosun 509T to FN MRD Pistols

Description

This Apex Optic Mount provides a direct, secure mounting solution for pairing the Holosun 509T red dot with FN 509 series pistols that feature the FN Low Profile Optics Mounting System™. Designed specifically for California customers who value reliability and compliance, this mount eliminates the need for stacking adapter plates or additional MRD inserts.

Machined from a single billet of steel and finished with a black oxide coating, this mount offers durability and corrosion resistance suitable for regular range use or defensive carry. The integrated locking key engages directly with the factory slide cuts, creating a solid interface that maintains zero over time. Because no separate MRD insert is required, installation is straightforward and the overall optic height remains lower than plate-based setups.

• Direct fit for FN 509 models – Works with FN 509, FN 509 Compact, FN 509 Tactical, and FN 545 pistols that include the FN Low Profile Optics Mounting System™. No adapter plates needed.
• Steel construction – Billet steel body with black oxide finish provides strength and resistance to wear, keeping the optic secure under recoil.
• Integrated locking key – Mounts directly to the slide without requiring a separate MRD insert, reducing parts and simplifying installation.
• Holosun 509T compatibility – Specifically designed to accept the Holosun 509T footprint, including both standard and X2 versions (sold separately).
• No plate stacking – Eliminates the extra height and potential failure points caused by stacking multiple mounting plates. The optic sits lower on the slide for a more natural sight picture.
• California-compliant design – Does not alter the firearm’s safety features or magazine capacity. Works with standard FN 509 and FN 545 slides as configured for retail sale in California.

Specifications & fitment: This mount is compatible with FN 509 models equipped with the factory FN Low Profile Optics Mounting System™, including full-size, compact, and tactical variants, as well as the FN 545. It accepts the Holosun 509T (and 509T X2) red dot sight using the factory included screws. Installation requires basic hand tools and the ability to remove the factory cover plate. The steel body adds minimal weight over the stock plate while providing a rigid mounting surface. Price: $60.

For customers in California who own an FN 509 or FN 545 and want to add a Holosun 509T without the hassle of plate adapters, this Apex mount delivers a clean, secure, and direct attachment method. It keeps the optic low, the installation simple, and the system