Apex Optic Mount for RMSc/507K – FN 509

Description

If you own an FN 509 with the factory MRD cut, you already know the challenge of finding a reliable mounting solution for compact red dots like the Holosun 507K or Shield RMSc. The Apex Optic Mount solves that problem directly. It is machined from a solid billet of steel, not cheap aluminum, and finished in a durable black oxide that resists holster wear and corrosion. This mount is built to handle the recoil of daily carry, range training, and hunting sidearms without loosening or flexing.

This mount is engineered specifically for the FN Low Profile Optics Mounting System™ found on FN 509 Tactical and MRD models. It does not require any adapter plates or modification to your slide. The steel construction provides a rock-solid base for your optic, which means your zero stays consistent shot after shot. For concealed carry, that reliability is critical — you don’t want to be re-zeroing after every range trip.

Fitment and installation is straightforward. If you are mounting a Shield RMSc, use the “514” screws that came with your FN 509 Tactical or MRD pistol. If you are mounting a Holosun 507K, use the screws included with the Apex mount. No filing, no fitting, no guesswork. The mount accepts both optics securely using the factory recoil lugs on your slide.

• Material: Billet steel with black oxide finish — stronger and more rigid than aluminum alternatives.
• Compatibility: FN 509 models with the Low Profile Optics Mounting System (MRD cut).
• Optics supported: Shield Sights RMSc and Holosun 507K (direct mount, no adapter needed).
• Hardware: Use FN 514 screws for RMSc; use included screws for 507K.
• Price: $65 — a simple, affordable upgrade that keeps your optic locked in place.

For the practical shooter, this mount eliminates the weak link between your pistol and your dot. Whether you are running drills, hunting hogs, or carrying concealed, you want your optic to stay put. The Apex mount does that without adding unnecessary height or bulk to your slide. It keeps the optic low enough to co-witness with standard-height iron sights on most FN 509 models.

This mount is also a smart choice for the FN 545 platform. If you are running a Holosun 507K on that pistol, the same direct-fit advantage applies. No plates, no shims, no extra parts to lose. Just a solid steel mount that does one thing and does it well.

At $65