Apex Optic Mount for Holosun 509T to FN MRD Pistols

Steel optic mount for mounting the Holosun 509T to FN 509-series pistols equipped with the FN Low Profile Optics Mounting System™. Eliminates the need for stacking adapter plates or MRD inserts by integrating the locking key directly into the mount body. Machined from billet steel with a black oxide finish for corrosion resistance and secure optic retention.

Compatibility

• FN 509 (all generations with FN Low Profile Optics Mounting System™)
• FN 509 Compact
• FN 509 Midsize
• FN 509 Tactical
• FN 509 LS Edge
• Holosun 509T (all revisions)
• Does NOT fit FN 509 without factory MRD cut

Key Features

• Billet steel construction, black oxide finish
• Integrated locking key – mounts directly to slide, no MRD insert required
• Zero stacking plates – single-piece design reduces failure points
• Maintains factory iron sight co-witness height
• Includes mounting hardware (verify thread pitch before install)

Install Difficulty: 2/5

Requires: Torx T10 driver, thread locker (blue Loctite 242 recommended), torque wrench (15 in-lbs for optic screws). Remove factory optic cover plate, clean mounting surface, apply thread locker, torque mount screws to spec, then mount 509T per optic instructions. No slide modification required.

FAQ

Does this work with the FN 545?

Yes – the FN 545 uses the same FN Low Profile Optics Mounting System™ as the 509 series. This mount is compatible with both 509 and 545 slides.

Will my iron sights still co-witness?

Yes – the mount is designed to maintain factory-height rear iron sight clearance. Co-witness depends on front sight height; factory FN sights will co-witness with standard-height optics.

Can I use this mount with a different optic?

No – this mount is specifically machined for the Holosun 509T footprint. Other optics will not fit without separate adapter plates.

Shipping & Warranty

Ships within 1-2 business days via USPS Priority or UPS Ground. This component carries a limited lifetime warranty against manufacturing defects from Apex Tactical. Return in original packaging within 30 days for refund or exchange.