Holosun HS510C Spacer for lower 1/3 Mount
The Holosun HS510C Spacer is a simple add-on that bumps your HS510C red dot up to a lower 1/3 co-witness height. Basically, it lifts the optic slightly so your iron sights sit in the lower part of the window instead of right in the middle, giving you a cleaner sight picture while still keeping backups visible. It installs between the optic and the mount, adds almost no weight, and is made from solid aluminum so it still holds up to recoil and rough use. It’s a cheap, easy upgrade that just helps dial in your setup without changing anything major.
-Nathan (Technical Advisor)
- Window Size: 0.58x0.77
- Dimension (in): 1.6x0.98x0.95
- Weight (oz): 1
- Housing Material: 6061 T6 Aluminum
- Surface Finish: Anodize
Optimal Height Adjustment: Elevates 510C optics to a lower 1/3 cowitness height (approximately 1.6 inches), facilitating quicker target acquisition and improved sight alignment.
Sturdy Construction: Machined from high-quality aluminum for robustness and resistance to recoil, providing a stable platform that maintains zero under rigorous use.
Easy Installation: The 510C Spacer mounts securely between the 510C optic and the quick-detach (QD) mount, offering straightforward installation without compromising on security.
Enhanced Compatibility: Designed to fit seamlessly with most 510C optics and QD mounts, ensuring compatibility across various firearm platforms and setups.
Precision Engineering: Features precise machining and a secure fit to prevent movement during recoil, ensuring consistent accuracy shot after shot.
1. What does this spacer do?
It raises the Holosun HS510C to a lower 1/3 co-witness height for better sight alignment.
2. What is lower 1/3 co-witness?
It means your iron sights sit in the lower third of the optic window instead of directly centered, giving a less cluttered view.
3. How much does it raise the optic?
It lifts the sight to about 1.63 inches above the rail.
4. Is it compatible with all Holosun optics?
It’s specifically made for the HS510C footprint, not universal across all models.
5. Does it affect zero?
No, it doesn’t change your optic’s zero—it only changes height position.
6. What is it made from?
Machined aluminum for strength and recoil resistance.
7. Does it add a lot of weight?
No, it’s extremely light—around 1 oz.
8. Is installation complicated?
Not really—it mounts between the optic and existing QD mount with standard screws.
9. Why choose lower 1/3 instead of absolute co-witness?
Lower 1/3 gives a cleaner view through the optic while still keeping irons as backup reference.
10. What’s the main benefit?
It fine-tunes your optic height for a more comfortable and less cluttered sight picture without changing your whole mounting system.
- Holosun 10 years / product lifetime warranty. Read more here
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