Red dot sight reviews
Holosun 510C Review
Quick answer
The Holosun 510C at $295.84 pairs a precise 2 MOA dot with a 65 MOA circle that covers 68 inches at 100 yards, finding your eye far faster than a bare dot up close, backed by a solar cell that keeps the sight running if the battery dies.
A single small dot is precise and slow to find under stress. A single large circle is fast to find and useless for a deliberate shot at distance. The Holosun 510C's Multi-Reticle System exists to avoid choosing between the two: a 2 MOA dot for precision sits inside a 65 MOA circle for speed, switchable independently, in one sight with a battery backed by a solar cell.
This review is built from Holosun's own published specifications for the 510C, the exact MOA arithmetic both reticle elements allow, and the consensus of verified owner reviews. We did not test this sight in person.
On this page
- How big is the circle, actually, compared with the dot?
- What does the solar failsafe actually protect against, and what does it not?
- What does owner-review consensus say about switching between the dot and the circle?
- The compromise a 65 MOA circle brings to precise, deliberate shots
- A plain dot instead, and a compact alternative on a common footprint
How big is the circle, actually, compared with the dot?
The working
reticle diameter = MOA x 1.047 x (range in yards / 100)
Exact trigonometry from the published 2 MOA dot and 65 MOA circle. Exit pupil does not apply to a 1x reflex sight, so subtension is the meaningful precision figure here.
The 65 MOA circle covers 68.06 inches at 100 yards, over 32 times the diameter of the 2 MOA dot at the same distance, which is exactly why it finds your eye faster and why it stops being useful for precision once the dot is what you actually need.
Sourced figure
| Reticle element | 25 yd | 100 yd | 200 yd |
|---|---|---|---|
| 2 MOA dot | 0.52 in | 2.09 in | 4.19 in |
| 65 MOA circle | 17.01 in | 68.06 in | 136.11 in |
See the full reticle subtension chart for how this compares against a bare 2 or 4 MOA dot sight with no circle at all.
What does the solar failsafe actually protect against, and what does it not?
Holosun's published Solar Failsafe keeps the sight illuminated from ambient light when it is available, which covers a dead or missing battery outdoors in daylight. It does not help indoors, at night, or in deep shade, where the sight depends entirely on the CR1632 battery like any other electronic optic. Holosun publishes up to 50,000 hours of battery life from its Red Super LED, and pairs that with Shake Awake motion sensing so the sight is not burning through that runtime while sitting untouched in storage.
What does owner-review consensus say about switching between the dot and the circle?
The recurring positive theme is that the reticle switching genuinely works as marketed: owners consistently describe the circle as noticeably faster to pick up in a close, fast scenario and the dot alone as the natural choice once precision at distance matters more than speed. The Quick Detach mount and its published 1.41 inch dot height also draw repeated praise for making the sight easy to remove and reinstall without losing zero.
The recurring caution is button layout: several reviews describe needing to check the manual once to learn the reticle-cycling sequence, since it is not as immediately obvious as a single brightness dial.
The compromise a 65 MOA circle brings to precise, deliberate shots
A 65 MOA circle covering 68 inches at 100 yards is not a precision aiming reference at that distance, and it is not meant to be one. If the circle-dot combination mode is left active for a deliberate shot rather than switching to the dot alone, the circle can obscure enough of a distant target to make a precise hold harder rather than easier. Reading the manual once to learn the button sequence for switching reticle modes under time pressure is a real, if small, added step this sight asks for that a plain single-reticle dot does not.
The 510C is also still a point source of light for its dot element, and both the dot and the circle are diode-generated rather than etched into glass, so an astigmatic eye will see either reticle element smear rather than resolve cleanly, exactly like every other red dot on this site.
A plain dot instead, and a compact alternative on a common footprint
If the reticle-switching itself is more complexity than you want, the Vortex SPARC Gen II at $99.99 is a single 2 MOA dot with none of the mode-switching, reviewed separately. If you want a similar circle-dot idea in a smaller housing on the widely supported 507C mounting footprint, the Holosun HS507C-X2 at $232.99 is the compact alternative from the same maker.
| Model | Price | Magnification | Dot size | Motion activation |
|---|---|---|---|---|
 Holosun 510C Multi-Reticle 2 MOA Dot and 65 MOA Circle Open Reflex Sight | $295.84 | 1x | 2 MOA | Yes |
 Holosun HS507C-X2 Red 2 MOA Dot and 32 MOA Circle Open Reflex Sight | $232.99 | 1x | 2 MOA | Yes |
 Vortex SPARC Red Dot Sight Gen II, 2 MOA Dot | $99.99 | 1x | 2 MOA | - |
A dash means the manufacturer does not publish that figure. We leave it blank rather than estimating it.
How we chose
We did not test these optics in person and we never claim to. Picks are researched from manufacturer specification sheets, published optical and ballistic formulas, and the recurring themes in verified owner reviews. Every pick is matched to a real objective diameter, a real tube size, a real ring height or a real exit pupil rather than to a price bracket, and it is placed in the tier where its capability actually belongs. Where a figure is shooter convention rather than a sourced number we label it, and where a manufacturer does not publish a figure we leave it out instead of estimating it.
Sources
- Holosun published specifications for the 510C Multi-Reticle System
- Owner-review consensus on reticle switching and solar failsafe performance
Frequently asked questions
What is the Multi-Reticle System on the Holosun 510C?
A choice between three reticle states: a 2 MOA dot alone, a 65 MOA circle alone, or a circle-dot combination, cycled through the sight's illumination controls. The dot suits a precise, deliberate shot at distance, and the circle suits fast target acquisition up close, since it is far larger and easier for the eye to locate first.
How big is the 65 MOA circle at 100 yards?
68.06 inches, computed as 65 MOA times 1.047 inches per MOA at 100 yards. That is more than 32 times the diameter of the 2 MOA dot at the same distance, which is exactly why the circle finds your eye faster and why it is not meant for precise aiming once you are past close range.
What does the solar failsafe on the 510C actually do?
It keeps the reticle illuminated using ambient light when the battery is dead or missing, which works outdoors in daylight but not indoors or at night. It is a backup to the CR1632 battery rather than a replacement power source, and Holosun's own published battery rating is up to 50,000 hours from the Red Super LED with Shake Awake motion sensing active.
Does the 510C have shake awake to save battery?
Yes. Holosun publishes Shake Awake motion sensing for this sight, which deactivates the LED after a period without movement and reactivates instantly when the sight is touched or the rifle moves. That is what lets the published 50,000 hour battery figure apply to a sight stored on a rifle rather than one left continuously lit.
Is the Holosun 510C good for someone with astigmatism?
Not reliably. Both the dot and the circle are diode-generated points and arcs of light rather than an etched glass reticle, so an astigmatic eye will see either element smear rather than resolve cleanly, the same limitation every projected red dot reticle shares regardless of brand or reticle shape.
What mount does the 510C use?
Holosun publishes a Quick Detach mount with a 1.41 inch dot height for this model, built for fast installation and reinstallation without losing zero. Check that height against your own rifle's iron sights or riser stack before assuming it matches an absolute or lower third co-witness on your specific setup.
Researched, not professional advice. This page is compiled from published manufacturer specifications, published optical and ballistic formulas, and owner-review consensus, not hands-on testing. Figures described as a rule of thumb are shooter convention rather than sourced numbers, and they are labelled that way wherever they appear. Ballistic figures come from a point mass model using the ballistic coefficient the maker publishes, so treat them as a starting point and confirm them on paper at a measured distance. Confirm your firearm is unloaded with the action open before you mount, level, torque or bore sight anything. Verify a zero only on a supervised range or a safe, legal backstop, know what lies beyond your target, and follow the law where you hunt and shoot, including rules on land access and permitted cartridges.