Teardown: Learn How Red Dot Sights Work in 5 Minutes

Red dot sights are like the heads-up-display from Top Gun, except for guns! Want to know how red dot sights work? 

You came to the right place. 

After this read, you’ll sound like the smartest guy on the range. Just don’t overdo it, nobody likes a know-it-all!  

What is a reflex sight?

how red dot sights work

To learn more about red dots, we must know where they originated. A red dot sight is a modern version of the reflex sight (also known as reflector sight).

How does a reflex sight work?

A reflex sight is a device that produces projections of an image in the field of view. It uses reflective glass material that makes the image appear as if it’s right in front of the viewer. Being projected “to infinity” causes the “dot” or crosshair to stay on target no matter how much eye movement there is.

What is a Red Dot Sight?

AT3 Tactical RD-50 Micro Reflex Red Dot Sight Review

A red dot sight is an optical device that helps the shooter to aim better by placing a dot on the target.

How A Red Dot Sight Works

In a a red dot sight, a light-emitting diode (LED) is used to display a reticle onto a special lens that only reflects light from the LED. Red dot sights have 2 critical parts, the LED and a curved glass to reflect the light for the reticle. The glass of the plate is specially coated so it only reflects the light from the LED and lets the shooter look through it. This is to avoid disruption from other light sources. The reticle is created once the mirror reflects the light emitted by the LED onto it.

reflex red dot sights

Red dot sights can be closed or open styles. With closed sights, an additional lens at the front of a tube protects the light source from dirt, dust, and fog. With an open reflex sight, those parts are largely open to the environment, cutting down on bulk in your sight picture but exposing it to the external elements. Like the reflex sight, the projected image onto the center of the scope is fixed relative to your gun and seemingly at infinite distance, producing minimal parallax. This means that your rounds will land exactly where the dot is provided that your sight is zeroed properly, and you don’t have to worry about eye position for target acquisition. 

Once you have one, learn how to zero your red dot quickly with our comprehensive guide.

Red Dot Sight Features

Holosun red dot sight

Pros And Cons Of Red Dot Sights

Thinking about picking up a red dot sight? Here are the pros and cons:

  • Improved accuracy
  • Ideal at close to moderate distances
  • Vary in size so they can fit on all types of firearms, from rifles to pistols
  • They help you acquire your target faster
  • No magnification like red dot scopes, so they are not ideal for long-range shooting
  • As the distance increases, the reticle gets larger and is more difficult to see, resulting in decreased precision
  • Short battery life on high brightness

Red Dot vs Holographic Sight

holographic sight red dot reflex

Now we know that a red dot sight consists of an LED source and a specially-coated spherical mirror that reflects the emitted beam to the viewer’s eyes. 

A holographic sight, on the other hand, projects a hologram that gets created when the laser diode’s beam gets reflected several times on a series of mirrors. 

Let’s compare these two on different aspects to see which is better.


Holographic sights can handle huge amounts of force and more extreme temperatures compared to red dots. 


Wallet with cash

Holographic sights are more expensive than red dots because of the more complicated mechanism. 


When not used constantly, a red dot sight’s battery life can last up to 50,000 hours. While a holographic sight can only last 500-1,000 hours. 


Red dot sights have available models for most gun sizes. While holographic sights can only fit medium-sized firearms. 

Bottom line: Both optical devices are great. You just have to choose which suits you best.


Do red dot sights work at night?

Best Night Vision Rifle Scopes

The answer is yes. Red dot sights can function even in the dark, or in any type of lighting. All you need to do is assess how dark the surroundings will be. You can buy red dots that come with night vision or you can get those that are specially created for shooting at night. You also need to consider if the sight’s brightness is adjustable.

Are red dot magnifiers worth it?

outdoor shooting

Since red dot sights don’t have magnification, it can be difficult to aim at longer distances. So some shooters use magnifiers for easier sighting in. Red dot magnifiers are great investments especially if you’ll be shooting moving objects at long ranges.

Can you put a magnifier behind a red dot?

Vortex VMX-3T Magnifier With Red Dot

No, you need to mount the magnifier before the red dot. Red dots can be placed anywhere on your gun. But the magnifier needs to be next to your face for eye relief reasons. Eye relief is the required distance from the magnifier so your eyes can have a full view of the target. If you place the magnifier behind the red dot, all you can see is a dark picture. 

red dot reflex sight eye relief scope riflescope

2. How far can you see with a 3x magnifier?

As the name implies, a magnifier makes the target appear 2X, 3X, or 6X closer. It helps you see more clearly for distances more than a hundred yards.

3. How far can you see with a 3x magnifier?

red dots with maginifier mounted

Red dots are effective until around 100 yards. So a 3X magnifier allows you to see clearly up to 300-350 yards.

What does a red dot sight look like?

vortex venom mounted

As mentioned above, a red dot sight has a slightly tilted spherical glass and an LED. In most designs, the optics are housed by a metal cover. Some housing designs are tube-like, similar to telescopes. While others are open, with a flat base and a sturdy cover that supports the optics.

What does MOA mean on a red dot?

MOA stands for Minutes of Angle. This is the unit of measure that indicates the size of the dot and how much area it would cover relative to distance. A dot of 1 MOA is equivalent to about 1 inch in diameter at 100 yards.

How to shoot with a red dot sight

Red Dot on a Gun

Here are steps that you can follow if it’s your first time using a red dot sight.

  1. Mount the sight on your weapon.
  2. Adjust your brightness setting.
  3. Aim your gun.
  4. Sight in your red dot.
  5. Fire a few rounds and check if your bullets hit the target. If not, adjust your sight and repeat the previous steps.

What distance are red dot sights good for?

indoor shooting range

Red dot sights have an effective distance of 100 yards.

If you prefer an optic with fixed magnification, the ACOG is an excellent contender. Find out which is better between ACOG vs red dot to help you decide.

Are red dot sights accurate?

Yes, but only up to a hundred yards. If you want to use your red dot further than that, you will want to install a magnifier or purchase a red dot scope with magnification built-in.

Does the military use red dot sights?

Using Red Dot Sights

Yes. Red dot sights are often used by the military since they are excellent for quick target acquisition in close quarters.

Do you have to zero a red dot sight?

Yes, you do. See how to save ammo when you zero your red dot sight in this guide.


Now you know how red dot sights work and how helpful they are for hunting or competitive shooting. Next is choosing which red dot sight is best for you. Check out this review to help you decide.

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