Apex Optic Mount for RMSc/507K – FN 509

Description

The Apex Optic Mount is a direct-fit solution for FN 509 model pistols equipped with the FN Low Profile Optics Mounting System™. Priced at $65, this mount allows you to securely attach a Shield Sights RMSc or Holosun 507K to your slide without aftermarket modifications or adapter plates that may shift under recoil. Machined from billet steel and finished in black oxide, it provides a durable, corrosion-resistant platform that holds zero through repeated use.

Key Benefits for California Customers

• No slide milling required. This mount installs directly into the FN Low Profile Optics Mounting System™ cut already present on FN 509 Tactical and MRD models. You keep your factory slide intact and maintain compliance with California’s firearm modification laws.
• Secure fit for popular optics. The mount is precision-machined to accept both the Shield Sights RMSc and the Holosun 507K. For RMSc optics, use the “514” screws included with your FN 509 Tactical or MRD. For the 507K, use the screws provided with the mount. No guesswork, no loose hardware.
• Steel construction improves longevity. Unlike aluminum mounts that can wear or strip over time, the billet steel body resists deformation. The black oxide finish adds a layer of protection against sweat, humidity, and cleaning solvents.
• Low-profile design. The mount sits flush within the FN slide cut, keeping your optic close to the bore axis. This reduces torque on the mounting screws and helps maintain a consistent cheek weld with standard-height iron sights.

Specs & Fitment

• Compatible with FN 509 models that have the FN Low Profile Optics Mounting System™ (including FN 509 Tactical and MRD variants).
• Accepts Shield Sights RMSc and Holosun 507K footprint optics only.
• Mount dimensions match the factory cut depth — no shims or spacers needed.
• Includes mounting screws for 507K installation; RMSc users must use the screws from their pistol’s original kit.
• Black oxide finish on billet steel construction.

Why This Matters for Your Build

If you live in a state with magazine capacity restrictions or a handgun roster, maximizing the utility of a legal firearm is a priority. Adding a red dot to your FN 509 improves target acquisition speed without altering the firearm’s core design. The Apex Optic Mount installs with basic tools and does not require permanent modification, so your FN 509 remains fully compliant with California regulations