This optic mount replaces the factory multi-plate system on FN 509-series pistols equipped with the Low Profile Optics Mounting System™. It provides a direct, steel-bodied interface for ACRO-footprint optics, eliminating the need for the factory MRD insert and subsequent plate stacking. The integrated locking key indexes directly into the slide cut, reducing the total parts count and potential failure points in the optic-to-slide connection.
Compatibility
- FN 509 Compact MRD
- FN 509 Full Size MRD
- FN 509 Tactical (all generations)
- FN 509 LS Edge
- FN 509 Midsize MRD
- FN 545 MRD
- FN Reflex MRD (verify slide cut profile)
Supported Optics
- Aimpoint ACRO P-1 / P-2
- Steiner MPS
- Lead & Steel Pandora PB-3
- Any optic with an ACRO-format footprint
Key Features
- Machined from billet steel, black oxide finish
- Integrated locking key – no MRD insert required
- Direct slide mount eliminates plate stacking
- Retains factory iron sight plane (co-witness dependent on optic deck height)
- Includes necessary mounting screws
Install Difficulty: 2/5
Remove factory optics cover plate and any existing adapter plates. Clean slide recess. Apply thread locker (included) to screws, torque to manufacturer spec. No slide modification required. Tools needed: Torx driver (T10 or T15 depending on screw spec), torque driver recommended (12-15 in-lbs).
FAQ
Does this mount work with the FN Reflex MRD?
Yes – the Reflex MRD uses the same Low Profile Optics Mounting System™. Confirm your slide has the factory MRD cut before ordering.
Will this mount co-witness with factory suppressor-height sights?
With an ACRO P-2 or Steiner MPS, you will achieve a lower 1/3 co-witness using the factory FN suppressor-height sights. Deck height varies by optic; confirm your sight height if running a non-standard setup.
Do I need the Apex Super Clamp for the Steiner MPS?
We recommend it. The MPS clamping lugs are narrower than the ACRO spec; the Super Clamp expands the clamping range for a secure fit. Without it, the MPS may exhibit lateral play under recoil.
Shipping: Orders over $99 ship free within the continental US. Warranty: This component carries a limited lifetime warranty against manufacturing defects. Does not cover damage from improper installation, thread locker application, or use with non-compatible optics.
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