If you’ve been trying to mount a Holosun 509T on an FN 509 with the factory Low Profile Optics Mounting System, you already know the drill: stacking plates, fiddling with inserts, and hoping everything stays tight. This mount solves that. It’s a single-piece steel adapter that replaces the factory MRD insert and gives the 509T a direct, secure fit to the slide. No extra plates, no guesswork, just a solid mount that keeps your optic where it belongs.
Will this fit my gun?
This mount is made specifically for FN 509 models that use the FN Low Profile Optics Mounting System (the same pattern found on the 509 Compact, 509 Midsize, 509 Full Size, and 509 Tactical). It fits the Holosun 509T (both the standard and the X2 version).
- FN 509 Compact
- FN 509 Midsize
- FN 509 Full Size
- FN 509 Tactical
- FN 509 LS Edge
- FN 545 (same optic footprint)
Key features
- Machined from billet steel with a black oxide finish – tough and corrosion-resistant
- Integrated locking key replaces the factory MRD insert – no stacking plates needed
- Direct-mount design keeps the optic low and secure
- Specifically engineered for the FN Low Profile Optics Mounting System
Install difficulty: 2 out of 5
If you’ve removed an optic plate before, you can handle this. Tools needed: a small Torx driver (T8 or T10 depending on your screws) and a dab of blue Loctite. The mount drops into the factory cutout, and the 509T screws directly into it. Watch our install video on the product page if you want a walkthrough – it’s a 10-minute job.
Frequently asked questions
Does this work with the FN 509 without the Low Profile Optics Mounting System?
No. This mount is designed specifically for the FN Low Profile Optics Mounting System found on newer 509 models and the 545. If your slide has the older, larger optic cut, it won’t fit.
Do I need to buy any extra screws or plates?
No. The mount includes the integrated locking key, so you don’t need an MRD insert or any adapter plates. Use the screws that came with your Holosun 509T or the factory FN screws (check length – we recommend using the screws supplied with the optic).
Will this work with other Holosun optics like the 508T or 407C?
No. This mount is cut specifically for the 509T’s unique footprint (the one with the two large ears on the sides). Other Holosun models use a different pattern and won’t fit.
Shipping & warranty: We ship within one business day, and this mount is covered by our standard lifetime warranty against manufacturing defects. If something’s wrong, we’ll make it right – no hassle.
Reviews
There are no reviews yet.