Holosun Lower Spacer 510C – 1/3 CW

Product Description

The Holosun Lower Spacer 510C – 1/3 CW is a mounting riser designed to elevate the Holosun 510C red dot sight to lower third co-witness height. This spacer positions the optic window higher above the rail, allowing you to see your backup iron sights in the lower third of the optic window when both are aligned.

Lower third co-witness places the red dot at a more comfortable viewing height for many shooters, especially when wearing a plate carrier or shooting from unconventional positions. The elevated position reduces neck strain and supports a heads-up stance.

This spacer is specifically made for the Holosun 510C and mounts between the optic and your rail. It maintains the tool-free quick-detach feature that 510C users rely on for rapid mounting and removal.

Key Facts

• Product Name: Holosun Lower Spacer 510C – 1/3 CW
• SKU: HOL510CSPACER
• Purpose: Raises Holosun 510C to lower third co-witness height
• Category: Optic mounting accessories

What Lower Third Co-Witness Means

Lower third co-witness refers to the alignment between your red dot optic and backup iron sights. With this setup, your iron sights appear in the lower third of the optic window when you look through the red dot. The dot itself floats in the upper two-thirds of the glass, giving you an unobstructed view while still providing access to irons if your optic fails.

This differs from absolute co-witness, where the dot and front sight post occupy the same visual plane. Many shooters prefer lower third because the irons stay out of the way during normal use but remain instantly available without removing the optic.

Why Use a Riser with the 510C

The Holosun 510C sits relatively low when mounted directly to a Picatinny rail. For AR-15 shooters accustomed to raised optics, the stock height may feel too low, requiring an uncomfortable cheek weld or neck angle. Adding this spacer brings the sight line up to the height many shooters find more natural.

Plate carrier users especially benefit from the added height. Body armor pushes your shooting stance upright, and a lower third riser compensates by lifting the optic into your natural line of sight. The adjustment is small but often makes the difference between fighting your gear and working with it.

Compatibility and Mounting

This spacer is made specifically for the Holosun 510C model. It is not compatible with other Holosun models such as the 407C, 507C, or 508T, which use different footprints and mounting systems. If you run a different optic, you will need a spacer designed for that model.

The spacer installs between the 510C and your Picatinny rail. Call 817-393-4000 to confirm fit with your specific rail or mounting setup if you have questions about installation.

Buying from Western Sport in Roanoke, TX

Western Sport is a licensed FFL/SOT dealer and gunsmith shop serving North Texas and the DFW area since 2007. We carry scope rings and mounts along with a full selection of optics and accessories. Call 817-393-4000 to place an order or ask questions about compatibility with your setup.

Frequently Asked Questions

Q: Does the Holosun 510C lower spacer work with other Holosun models?

A: No, this spacer is designed specifically for the Holosun 510C. Other Holosun models like the 407C, 507C, and 508T have different footprints and require their own compatible spacers. Using the wrong spacer will result in improper fitment and an unstable mount.

Q: What is the difference between lower third and absolute co-witness?

A: Lower third co-witness places your iron sights in the bottom third of the optic window, keeping them visible but out of the main field of view. Absolute co-witness aligns the red dot and iron sights on the same plane, so both occupy the center of the window. Lower third is preferred by shooters who want an uncluttered sight picture with backup irons still accessible.

Q: Will this spacer fit on a Picatinny rail?

A: Yes, the spacer mounts to a Picatinny rail and raises the 510C to lower third height. The 510C with this spacer maintains the quick-detach system for tool-free installation and removal. If you are using a non-standard rail, call 817-393-4000 to verify compatibility before ordering.

Q: Can I still use my backup iron sights with this spacer installed?

A: Yes, the entire purpose of this spacer is to position the 510C at lower third co-witness height so your iron sights remain visible in the lower portion of the optic window. This setup gives you instant access to backup sights without removing the red dot.

Q: How do I know if I need a riser for my 510C?

A: If the stock mounting height of the 510C feels too low and forces you into an uncomfortable cheek weld or neck angle, a riser will help. Shooters using plate carriers or preferring a more upright head position typically benefit from lower third height. If you are unsure, call 817-393-4000 and we can walk you through the decision.

Q: Does Western Sport offer gunsmithing services if I need installation help?

A: Yes, Western Sport has on-site gunsmithing services in Roanoke, Texas. While installing a spacer is straightforward and typically does not require professional help, our gunsmiths can assist if you run into fitment questions or want to discuss your overall optic setup. Call 817-393-4000 to schedule a consultation.