Apex Optic Mount for RMSc/507K – FN 509

Description

The Apex Optic Mount for RMSc/507K is a direct-fit solution for FN 509 pistols equipped with the FN Low Profile Optics Mounting System™. Priced at $65, this mount bridges the gap between your factory slide and compact red dot optics, ensuring zero shift during high-round-count training or competition strings. It is machined from billet steel and finished in Black oxide, providing corrosion resistance and a low-reflective surface that holds up against holster wear and carbon fouling.

This mount is built specifically for shooters who demand absolute reliability on their duty rig or match gun. It eliminates the need for adapter plates that can introduce play or failure points. By using a direct-machined interface, the optic sits lower on the slide, co-witnessing more naturally with standard-height iron sights. This is critical for fast transitions on steel targets or threat-focused drills where every millisecond counts.

Key features and real-world benefits:

• Precision steel construction – Billet steel withstands the recoil impulse of full-power 9mm loads without flexing or cracking. Black oxide finish resists rust and glare.
• Designed for FN Low Profile Optics Mounting System™ only – This mount is machined to the exact dimensions of the FN 509 MRD cut. No shims, filing, or aftermarket slide modifications required.
• Compatible optics – Accepts Shield Sights RMSc and Holosun 507K directly. No additional plates or adapters needed for these popular compact dots.
• Included hardware – For the RMSc, use the “514” screws that came with your FN 509 Tactical or MRD model. For the 507K, use the screws included with this mount. Both are correctly pitched and torqued to prevent stripping.
• Secure zero retention – The mount clamps the optic against a flat, machined surface. This prevents lateral shift from slide cycling or impact, keeping your point of aim consistent round after round.

Fitment notes:

• Compatible with FN 509 series pistols that have the FN Low Profile Optics Mounting System™ (MRD cut slides).
• Also fits the FN 545 when using the same optic cut configuration.
• Does not fit standard FN 509 models without the MRD cut. Verify your slide has the Low Profile Optics Mounting System™ before ordering.
• Optic footprint is RMSc/507K (Shield RMS/RMSc, Holosun 507K/407K, Swampfox Sentinel, and similar).