Apex Optic Mount for Holosun 509T Optic to Glock MOS Pistols

This optic mount is a direct-fit adapter plate designed to interface the Holosun 509T optic with Glock MOS-pattern slides. The primary problem it solves: the 509T uses a proprietary footprint that does not directly bolt to the standard MOS cut. This component bridges that gap with a steel-bodied, zero-shim interface, eliminating adapter stacking or custom milling. The result is a repeatable, rigid mounting solution that preserves co-witness potential with standard-height suppressor sights.

Compatibility

• Glock MOS models: G17 Gen5 MOS, G19 Gen5 MOS, G34 Gen5 MOS, G45 MOS, G47 MOS
• Holosun 509T (all generations, including 509T-X2 and 509T-RD)
• Factory Glock MOS slide cuts only. Not compatible with non-MOS slides or aftermarket RMR-cut slides without additional adapter plates.

Key Features

• Material: CNC-machined from billet steel, black oxide finished for corrosion resistance and low-glare surface
• Direct mount: replaces the factory MOS cover plate; uses the same four screw holes
• Hardware included: two 509T mounting screws (6-32 thread, correct length for MOS pocket depth)
• Torque spec: 15 in-lb for all four mounting screws (slide-to-plate and optic-to-plate)
• Co-witness: maintains lower-1/3 co-witness with standard-height Glock MOS suppressor-height sights
• Profile: low-profile, no overhang on slide width; no snag points on holster draw

Install Difficulty: 2 / 5

Basic armorer-level work. Tools needed: #6 hex driver (T6 or T8 depending on screw head), torque driver capable of 15 in-lb, blue Loctite (recommended but not included). Clean the MOS pocket with isopropyl alcohol before installation. Remove factory cover plate, position the mount, torque to 15 in-lb, then mount the 509T using included screws to the same torque value. No fitting, filing, or slide modification required.

Frequently Asked Questions

Does this mount require any permanent modification to the slide?

No. The mount uses the factory MOS screw holes. Installation is fully reversible. No slide milling, drilling, or removal of material is needed.

Will this work with a Glock 43X MOS or 48 MOS?

Yes. The 43X MOS and 48 MOS share the same MOS cut pattern as full-size Gen5 MOS slides. This mount fits those models without issue.

What screw torque should I use for the optic to the mount?

15 in-lb for all screws. Exceeding 18 in-lb risks stripping the MOS threads or damaging the optic housing. Use a calibrated torque driver—don’t guess.

Shipping: Ships same business day if ordered before 2 PM MST. Warranty: This component is covered by a limited lifetime warranty against manufacturing defects. Return it if it fails under normal use; we will replace it.