Description
The Holosun HS510C is an open reflex red dot built for rifles, carbines, PCCs, and shotguns. The draw is the window: it's a large, open, squared-off viewing area rather than a small tube, so it's fast to find the dot and easy to keep both eyes open and stay aware of what's around your target. It's one of Holosun's most popular rifle optics, and it has been for years, because it packs a lot of features into a working price.
It uses the Multi-Reticle System, so you get three reticle options: a precise 2 MOA dot on its own, a fast 65 MOA circle on its own, or the circle and dot together. The big 65 MOA ring is quick to pick up for close work, the bare 2 MOA dot is what you want for a precise shot, and you switch between them without losing zero. It comes in your choice of a red or green emitter.
One thing your typical open reflex sight makes you buy separately is a mount. The 510C doesn't: it ships with an integrated quick-detach mount that gives an absolute co-witness at 1.41" dot height, so it lines up with standard AR iron sights, throws on a picatinny rail in seconds, and comes back off without losing your zero. That's a real part of the value here.
For power it runs Solar Failsafe, which uses a solar panel to back up the CR2032 battery and keep the optic running if the battery dies, plus Shake Awake to sleep the optic when it sits still and wake it on movement. The housing is 6061 aluminum with a titanium hood over the lens for impact protection, and it's sealed to IP67. You can see the matching 510C ARD below and the rest of our red dots and optics here.
One honest note on battery life: Holosun's "up to 50,000 hours" figure is for the bare 2 MOA dot. If you run the MRS circle-dot reticle, real runtime is shorter because the ring draws more power. Either way it's long, and Solar Failsafe backs it up.
Cut the Glare
An open-emitter optic with a large lens shows glint and reflection in bright sun. The CovertArms Holosun 510C ARD is a honeycomb anti-reflection device cut for this optic's window to kill that reflection and add a layer of lens protection.
Reach Out Farther
Want to stretch past red-dot distance? The Holosun HM3X 3x magnifier pairs directly with the 510C (Holosun sells the two as a combo) and flips to the side when you don't need it. For more power, the HM6X 6x magnifier is the longer-range option.
How It Compares
If you want a similar large-window feel in an enclosed, more weather-sealed design, the Holosun AEMS Core X2 is the enclosed-emitter step up. For a holographic option in the same rifle role, the EOTECH 512 is another large-window choice we carry.
Key Features
- Large open window. Wide, squared viewing area for fast dot pickup and situational awareness.
- Multi-Reticle System (MRS). Selectable 2 MOA dot, 65 MOA circle, or both, switched without losing zero.
- QD co-witness mount included. Integrated quick-detach mount at 1.41" absolute co-witness height, no extra mount to buy.
- Solar Failsafe. Solar panel backs up the battery and keeps the optic running if it dies.
- Shake Awake. Sleeps when idle, wakes on motion.
- Titanium hood. 6061 aluminum housing with a titanium hood protecting the lens.
- Red or green reticle. Available in both emitter colors.
Specs
- Type: Open reflex rifle/carbine red dot
- Reticle: MRS, selectable 2 MOA dot / 65 MOA circle / both
- Reticle color: Red (650nm) or Green (540nm)
- Magnification: 1x, parallax-free, unlimited eye relief
- Housing: 6061 aluminum with titanium hood
- Sealing: IP67 waterproof
- Brightness: 12 settings (10 daylight, 2 night vision)
- Battery: CR2032
- Battery life: Up to 50,000 hours with 2 MOA dot (shorter with MRS reticle)
- Power backup: Solar Failsafe
- Mount: Included QD mount, 1.41" absolute co-witness, picatinny
- Weight: ~8.3 oz
FAQ
Does the 510C come with a mount?
Yes. It ships with an integrated quick-detach mount at 1.41" dot height, which gives an absolute co-witness with standard AR iron sights. You don't need to buy a separate mount to put it on a rifle.
What's the Multi-Reticle System?
It's a selectable reticle. You can run a 2 MOA dot alone, a 65 MOA circle alone, or both together, and you switch between them without losing zero. The big circle is fast up close, the dot is precise at distance.
Red or green dot, which should I pick?
Green is often easier for some eyes to see in bright daylight, while red draws slightly less power. Both use the same MRS reticle and the same housing. It comes down to preference.
What does Solar Failsafe do?
A solar panel on top supplements the battery and keeps the optic running even if the battery dies, and it helps manage brightness automatically in changing light.
Is the battery replacement toolless?
No. The battery is in a bottom tray and the optic ships with a T10 Torx wrench and a battery tool for replacement. Plan to keep those with your kit.
Can I add a magnifier?
Yes. The Holosun HM3X 3x flip-to-side magnifier is built to pair with the 510C and Holosun sells them as a combo. The HM6X is the higher-magnification option.
