This screw set replaces the factory optic mounting hardware on FN MRD (Micro Red Dot) pistols fitted with an Apex Tactical optic mount for RMR footprint optics. The factory screws supplied with many Holosun optics are often the wrong thread pitch or length for the Apex mount, causing poor retention, stripped threads, or zero shift under recoil. This dedicated set provides the correct thread engagement and torque spec for a secure, repeatable mount.
Compatibility
- FN 509 MRD series (all generations)
- FN 545 MRD
- FN 510 MRD
- FN Reflex MRD
- Fits Apex Tactical optic mounts for FN MRD pistols (RMR footprint only)
- Compatible with Holosun 407C, 407K, 507C, 507K, 508T, 509T, 507Comp, and EPS series optics (requires Apex RMR-to-K or RMR-to-EPS adapter plate for K/EPS footprints)
- Does NOT fit factory FN optic mounting plates
Key Features
- Precision-ground 6-40 thread pitch screws (two included)
- Correct length optimized for Apex mount + FN slide stack-up (no bottoming out)
- Black oxide finish for corrosion resistance
- Includes 2.0 mm hex drive socket head
- Tested to 25 in-lb torque spec without thread deformation
- Sold as a pair (left/right orientation)
Install Difficulty: 2/5
Requires a 2.0 mm hex driver (not included) and a torque wrench capable of 15–25 in-lb. Remove existing screws, clean threads with isopropyl alcohol, apply blue Loctite 242 to the new screws, and torque to 18 in-lb. Do not exceed 25 in-lb. No slide disassembly or gunsmithing required.
FAQ
Will these work with a Trijicon RMR Type 2 on the Apex mount?
Yes. The 6-40 thread pitch matches Trijicon RMR screws. Verify the screw length does not exceed the Apex mount’s thread depth (approx. 0.25”). If using a sealing plate, reduce torque by 2–3 in-lb.
Why can’t I use the screws that came with my Holosun optic?
Holosun optics typically ship with M3 x 0.5 metric screws. The Apex mount is threaded for 6-40 (imperial). Forcing metric screws into 6-40 threads will strip the mount and void the warranty. This set provides the correct imperial thread for the Apex mount.
Are these screws reusable after removing the optic?
Yes, provided they show no thread galling, deformation, or Loctite buildup. Clean old Loctite with a wire brush and reapply fresh 242 before reinstallation. Replace if the hex socket rounds out or the screw head shows wear.
Shipping: Ships USPS First Class within 1 business day. Warranty: Apex Tactical covers manufacturing defects. This screw set is a consumable item; damage from over-torque, incorrect thread pitch, or improper installation is not covered.
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