If you’ve got an FN MRD pistol with an Apex optic mount, you know that keeping your red dot locked down tight isn’t optional. This screw set from Apex is built specifically for that setup — no guesswork, no mixing parts from different kits. It’s a direct replacement for the screws that hold your Trijicon RMR or any other RMR-footprint optic to the Apex mount on your FN pistol. At $20, it’s a cheap fix if you’ve lost a screw, stripped one during installation, or just want spares on hand for the range bag or your shop’s inventory.
What you’re getting:
- Exact fit for FN MRD pistols with an Apex mount: These screws are machined to match the thread pitch, length, and head profile required for that specific combo. No filing, no shims, no “close enough.”
- RMR footprint compatibility: Works with Trijicon RMR (all generations), Holosun 407C/507C/508T, Swampfox Liberty/Justice, Vortex Viper/Venom, and other optics using the same hole pattern.
- Solid steel construction: Hardened to handle torque without twisting or snapping under recoil. Threads are cleanly cut for a smooth install with standard hex keys.
- Cost-effective spare set: At $20, it’s cheaper than hunting down a single OEM screw from the manufacturer or buying a whole new mount just for hardware. Grab a few sets to keep on the shelf or toss in your tool box.
Specs & fitment:
These screws are designed for the Apex Tactical optic mount used on FN 509, FN 509 Compact, FN 509 Midsize, FN 509 Tactical, FN 545, and FN 510 models that are factory-milled for MRD optics. They also fit the Apex mount that replaces the original FN factory plate. The thread size is 6-40 with a length that matches the Apex mount’s pocket depth — too long and you’ll bottom out or interfere with the extractor, too short and your optic will shake loose. These are the right length. Use a 3/32” hex driver (not included) and apply a dab of blue threadlocker (not included) to each screw before torquing to the mount’s specified inch-pounds.
Why buy from us:
We stock these in bulk because they’re a common replacement part for anyone running a red dot on an FN. No fancy packaging,
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