Apex Optic Mount for FN MRD Pistols to mount RMR Footprint Optics

If you’ve got an FN MRD pistol with the Low Profile Optics Mounting System™, you know the factory cut is a little different from the standard RMR footprint. This optic mount bridges that gap—letting you securely attach an RMR-footprint red dot directly to your slide without needing a separate key insert or adapter plate. It solves the “will my RMR fit this FN slide?” headache in one simple piece.

Compatibility

• FN 509 Series (all MRD models)
• FN 509 Compact MRD
• FN 509 Tactical MRD
• FN 509 Midsize MRD
• FN 509 Edge
• FN Reflex MRD (RMR-footprint optics only)
• Fits any FN slide with the factory Low Profile Optics Mounting System™ cut

Key Features

• Direct-fit mount – no MRD Key Insert or adapter plates required
• Pre-applied High-Temperature Thread Locking patch on the screws – no liquid thread locker needed, just torque and go
• Low-profile design keeps your optic close to the slide for a clean sight picture
• Precision-machined steel construction for repeatable zero retention

Install Difficulty: 2 out of 5

Easy to moderate. You’ll need a small flathead or Torx driver (depending on your optic), a torque wrench or driver set (recommended 15 in-lbs), and about 10 minutes. The pre-applied thread locking patch means you don’t have to mess with messy liquids. Watch our install video on the product page—it’s straightforward.

Frequently Asked Questions

Will this mount work with my FN 509 if I already have a different optic cut?

Only if your slide has the factory FN Low Profile Optics Mounting System™ cut. If your slide was cut for a different footprint (like a standard RMR or Doctor cut), this mount won’t fit. Check the bottom of your slide—if you see the MRD key insert, you’re good.

Can I use this mount with a Holosun 507C or 508T?

Yes, any optic that uses the RMR footprint—Holosun 507C, 508T, Trijicon RMR Type 2, SRO, and similar—will work. The mount positions the optic at the correct height for co-witnessing with standard-height iron sights.

Does this mount come with screws?

Yes, it includes the necessary screws with pre-applied High-Temperature Thread Locking patch. No liquid thread locker needed. Just torque to spec and you’re set.

Shipping & Warranty

We ship this mount within one business day from our shop in central Texas. It’s covered by our standard 1-year warranty against manufacturing defects. If something’s off, we’ll make it right—just give us a call or send an email. Questions about fit? We’re happy to help before you order.