OSA Glock 43X/48 MOS Conversion – Holosun 507K / 407K / EPS / EPS Carry

Already have a Glock 43X MOS or Glock 48 MOS? This conversion service modifies your factory MOS slide to allow the Holosun 507K, 407K, EPS, or EPS Carry to mount directly to the slide—eliminating bulky adapter plates and creating a stronger, lower-profile optic installation.

By machining the factory MOS footprint, your optic sits lower, improving your sight picture, increasing screw engagement, and providing a more secure mounting solution for everyday carry.

Compatible Optics

Holosun 507K
Holosun 407K
Holosun EPS
Holosun EPS Carry

Service Includes

Precision modification of your factory Glock 43X/48 MOS slide
Removal of factory rear indexing posts
Front indexing posts shortened for direct optic mounting
Slide disassembly and reassembly
Iron sight installation (if provided)
Optic mounting screw modification
Choice of finish:
- Optic Cut Only (Cold Blue)
- Single Color Cerakote
- Camo Pattern Cerakote

Screw Modification

To ensure proper fit and thread engagement, mounting screws are modified during the conversion.

Customer-supplied Holosun screws are preferred.

If needed, we can modify standard Holosun screws to the proper length:

507K / 407K: Trimmed to 0.400" OAL
EPS / EPS Carry: Trimmed to 0.360" OAL

Iron Sight Compatibility

Depending on your preferred sight picture, we recommend the following:

Lower 1/4 Co-Witness

Factory Glock Sights
AmeriGlo (.180" Front / .256" Rear)

Lower 1/3 Co-Witness

AmeriGlo (.240" Front / .335" Rear)

Our Thoughts

The factory Glock MOS system is incredibly convenient—but for the slimline pistols, it's not ideal if you're planning to run a Holosun K-Series optic.

Using an adapter plate raises the optic higher than necessary, adds another component that can loosen over time, and often requires taller backup sights.

Our MOS Conversion solves those problems by machining the factory slide so the optic mounts directly to the slide, creating a stronger interface while lowering the optic enough to improve both presentation and co-witness.

The result is a cleaner installation, better screw engagement, and a pistol that simply feels more refined.

For many concealed carriers, the Holosun EPS Carry has become the ideal optic for the 43X and 48 thanks to its enclosed emitter, compact footprint, and outstanding durability. This conversion allows you to take full advantage of that optic without compromising the mounting system.

Turnaround & Shipping

Current Lead Time: Approximately 2–3 Weeks
Please include a copy of your order invoice when shipping or dropping off your slide.

Professional Machining

OSA partners with Battle Werx, one of the industry's leading optic machining specialists, to perform all optic cut services. Every slide is professionally machined, inspected, and returned ready for years of dependable use.

Patent Information

This service incorporates patented optic cut technology pioneered by ZEV Technologies (U.S. Patent RE47335), providing an industry-proven mounting interface designed for exceptional strength, repeatability, and long-term reliability.