If you’ve got an FN 509 with the factory Low Profile Optics Mounting System™, you already know the struggle of stacking adapter plates just to mount a red dot. That extra height can mess with your sight picture and add unnecessary bulk. This optic mount solves that problem by letting you attach an Aimpoint ACRO, Steiner MPS, or any ACRO-footprint optic directly to the slide—no MRD insert needed. It’s machined from solid steel with a black oxide finish, so it’s tough enough for range days, classes, or just plinking in the backyard.
Will This Fit My Gun?
- FN 509 series with the FN Low Profile Optics Mounting System™ (factory MRD cut)
- FN 545 (same mounting system)
- FN 510 (same mounting system)
- Does not fit standard FN 509 without the factory optic cut
Optics Compatible
- Aimpoint ACRO P-1 and P-2
- Steiner MPS
- Lead & Steel Pandora PB-3
- Any optic with an ACRO footprint (verify your optic’s base pattern)
Key Features
- Integrated locking key mounts directly to the slide—no separate MRD insert required
- Machined from billet steel, black oxide finish for corrosion resistance
- Eliminates the need for stacking plates, keeping your optic low to the bore
- We recommend pairing with the Apex Super Clamp if you’re using an MPS optic—it expands the clamping range for a more secure fit
Install Difficulty
Difficulty: 2 out of 5 — Medium. You’ll need a torque wrench (inch-pounds), blue Loctite, and the appropriate bit for your optic’s screws. The mount itself bolts directly to the slide without any extra parts. Watch our install video on the product page if you’re unsure—it’s straightforward, but proper torque matters.
Short FAQ
Will this mount work on my FN 509 Compact?
Yes, as long as your Compact has the factory FN Low Profile Optics Mounting System™ cut. Check the top of your slide—if it has the two small screw holes and a recessed pocket, you’re good.
Do I need to use the Apex Super Clamp with my Steiner MPS?
We strongly recommend it. The MPS has a slightly different clamping design than the ACRO, and the Super Clamp ensures the optic stays put under recoil. It’s a cheap add-on for peace of mind.
Can I use this mount with a suppressor-height sight co-witness?
Yes, with most standard-height suppressor sights. The low-profile design keeps the optic close to the slide, so you can still see your irons through the window. Test fit with your specific sights to be sure.
Shipping & Warranty
We ship within 1-2 business days from our shop. This mount comes with a limited lifetime warranty against manufacturing defects—if it cracks or warps from normal use, we’ll replace it. No questions asked.
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