Red Dot Sight Complete Beginner Guide

This red dot sight complete beginner's guide will go from A to Z breaking down benefits of using a red dot sight on a modern firearm in simple terms, important things to understand, and some pro tips for shotguns, pistols, and rifles.

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fn scar 17 with aimpoint micro

Red dot sight is invented in the mid-70s, and now it's one of the most popular 1X optics shooters buy for rifles, shotguns, and handguns to aim & shoot accurately.

A red dot sight works by projecting a very small LED dot reticle from the LED emitter to the coated, slightly angled piece of the front glass.

Then the shooter sees the aiming reticle.

Difference Between Reflex Sight And Red Dot Sight

Reflex red dot and red dot are pretty much the same things.

Reflex sights are typically associated with open emitter sights like the Trijicon RMR. Red dot sights are reflex sights enclosed in a body like the Aimpoint

Red Dot's Primary Benefits

The primary benefit of a red dot sight is to eliminate the need for traditional sight alignment, so the shooter can point the dot where it needs to be and the bullet will go there (When zeroed)

In addition, a red dot sight provides the following undeniable capabilities that people absolutely love:

Fast Target Acquisition

shooting ddm4v11 with aimpoint micro h1

The center bright dot reticle draws the eye to the center as soon as the shooter draws the firearm. The bigger the window the faster it is.

No rear, front sight & target plane alignment required - cuts target acquisition time significantly

Aim With Both Eyes Open

trijicon sro on fnx 45 tactical

Keep both eyes open and focus on the target plane, and just let the dot superimpose on top of the target.

  1. Both eyes open maximizes situational awareness in the peripheral
  2. Train to aim with both eyes open helps a lot in flight or fight situations

Adds 1X Capability To A Long Range Rifle

offset scar 17 valhalla tactical rukh mount

Shoot long range with a magnified rifle scope, then transition to the 1X red dot for close-range targets.

Parallax Free

deltapoint pro parallax

Since no alignment is required between the target plane, front sight, and rear sight. The shooter has a way more flexible eye box without having to directly align the eye behind the optic.

This means the shooter can be slightly off-center, and still get on target at the effective ranges, but there are some caveats, which we will discuss below.

The #1 Difference Between Red Dot & Holographic

How holographic sight works

The number 1 difference between a red dot sight and a holographic sight is the way the reticle is projected onto the lens.

A red dot sight's LED emitter projects the beam towards the front glass then simply reflects back to the shooter's eyes.

Vortex amg uh 1 gen 2 kriss vector

A holographic sight works the same way, but it reflects the laser reticle a couple more times off the mirrors to send a hologram back to you.

There are specific scenarios where a red dot is better than a holographic sight, and vice versa, which we will discuss in the Pro Tips section of this guide.

Things To Understand

Dot Sizes

3 moa vs 6 moa dot sizes comparison

Most new shooters pick dot sizes randomly until someone points out their differences!

There are many different dot sizes ranging from 1 MOA to as big as 12 MOA. The most common dot sizes are:

  • 1 MOA - The smallest dot available for precise aiming
  • 2 MOA - 2.5 MOA - The most common for products like Aimpoint Micro, Holosun and others
  • 3 MOA - Great sweet spot between a big dot and a small dot
  • 5 - 6 MOA - Highly recommend for shotguns, pistols and shooters with astigmatism
holosun hm3x with leupold lco pov

1 MOA dot covers about a 1" diameter circle at 100 yards (Much better for precise aiming)

2 MOA dot covers about 2" diameter circle at 100 yards

6 MOA dot covers about 6" diameter circle at 100 yards (Bigger and faster for the eye to pick up)

If you're buying your first red dot sight, which one should you go for?

To simplify this:

For pistol & shotgun shooters, go with anything 3 MOA or 6 MOA

springfield xdm trijicon sro
benelli m4 aimpoint micro

For rifle shooters, stick with 1 - 2 MOA

daniel defense m4a1 aimpoint micro red dot

For shooters with astigmatism, a bigger dot is always helpful

Elevation & Windage Adjustment

Most red dot sights on the market feature 0.5 MOA / Click adjustments. Most micro red dot sights like the RMR feature 1 MOA / click.

0.25 MOA / click adjustment is typically found on precision rifle scopes.

When zeroing the red dot sight, please follow this simple equation:

Exact number of clicks to dial = # inches missed / (yard distance / 100) / 0.5 MOA

zeroing red dot 100 yard

7" / 0.1 = 70 MOA missed to the left

3" / 0.1 = 30 MOA missed high

70 MOA / 0.5 MOA per click = 140 clicks to the right needed

30 MOA / 0.5 MOA per click = 60 clicks to down needed

The adjustment turrets direction (Up / Right) reference the point of impact instead of the point of aim. 

adjust MOA

Take another 3 shot group to verify the zero. May need some micro adjustment. We highly recommend zeroing the rifle on a steady tripod.

point of aim is point of impact

Now the point of aim is point of impact

If you get confused on why the shot group moves in the opposite direction of the turrets dial, please check out this guide

Astigmatism

Shooters with astigmatism will see this:

shooters with astigmatism see this
DD MK18 with Aimpoint Micro H1

Most red dot sights on the market have very crispy reticle if seen under a camera, but looks blurry, dotted, stretched or smeared with the human eye.

astigmatism eyes looking at night
eye shape astigmatism

In fact, most people have some levels of astigmatism because the human eye is never perfectly round. So the light entering the cornea will refract until wearing corrective lenses.

Other blurry reticle problems could be caused by:

  • Brightness turned up too high while using a small dot - The emitter starburst is very visible and covers up the dot itself
  • Facing direct sun light
  • Sensitive auto brightness adjustment sensor

The user can adjust the brightness, squinting the eye to see better, but the real solution is to correct the eye vision first.

The other good option is to switch to prism optic.

Eye Dominance

Eye dominance do affect shooters using red dot sights.

Most shooters aim with their dominant eye on the same side of their dominant hand.

Other shooters however may be cross-eye dominant. Cross eye dominant shooters can train to shoot with both eyes open with pistols, but had to learn to aim with the non dominant eye with on the same side as the dominant hand.

Window Size

Trijicon sro front glass

A bigger window size eliminates the frame obstruction, and it gives the rifle shooter a wider field of view and maximizes peripheral situational awareness.

For pistol users, picking up the dot can be challenging to center the dot about 17" away from the eye through a small window.

fnx45 with holosun 507c pov

Learn ways to acquire the dot faster with a pistol here

Leupold LCO X95 POV

Newer red dot sights like the Leupold LCO and Trijicon MRO eliminates the tube effect to widen the field of view so the shooter doesn't get the tunnel effect. Even though it's not too bad, but companies are designing better products to make things better.

A big window also helps pistol shooters tremendously to acquire the dot fast, reacquire the dot faster, and not lose the dot inside the window.

So the shooters can move their heads with more flexibility without the perfect optic to eye alignment, and still acquire the dot.

Parallax

Aimpoint Micro H1 on X95 POV

Most red dots and holographic sights are marketed as parallax-free, but they are not always 100% especially at close distances.

See below:

Click here to see our parallax tests for 12 different red dots

Emitter Glare Reflection

red dot brightness dialed up too high

Emitter glare can easily be fixed by dialing down the brightness settings.

It's very helpful to eliminate the glare reflection in low-light situations so that the LED emitter doesn't reflect back on the front glass.

Interesting fact - Holographic sights don't have that problem because the reticle isn't reflected back to the front glass

Brightness Adjustment

red dot brightness dialed up too high

Most red dot sights have plenty of brightness adjustment range to accommodate the lighting environment.

sig sauer romeo5 top view

For daytime use, crank it up

For nighttime use, crank it down.

We have a detailed guide on this topic, click here to read more

Battery Life

sig romeo 5 with battery CR2032

50,000 hours is the standard battery life for most red dot sights on the market today. That's about 5+ years of battery life, so the users can confidently leave the optic alone and it's always on and ready.

In addition, companies like Holosun, Sig Sauer, and many other companies are introducing motion sensors & solar panel technologies to keep these optics working even longer.

Motion sensor activates the reticle upon motion and turns it off while sitting idle to save battery juice

Solar panel acts like a fiber optic on an ACOG scope to power the reticle under any light source even if the battery runs out.

NEED TO KNOW: Red dot sight's battery life far exceeds holographic sight.

Durability & Mounts

scalarworks aimpoint acro mounts

Red dot sights contain electronic components that can shift inside the enclosed body if it's not well made. That means they can lose zero overtime.

The reason why some red dot sights cost more than the cost of a Glock 17 pistol is because of the amount of work & materials that get put into making them.

They are tough and can handle drops, sharp recoils, bumps, and other field stress.

The optic mount is another critical component to secure the optic on the firearm, so it can hold it tight in place, ensure zero repeatability, and absorbs recoil forces.

Handgun Slide Mount

chwps rmrcc hellcat adapter

Micro red dot sights like the Trijicon RMR, Holosun 507C, Holosun 507K, Vortex Venom and many others can be mounted on handguns.

The handgun slide must be milled or manufactured right out of the box to accept these optics. Some require aftermarket plates or custom fitting.

Pro Tips

Practice, Practice, Practice

fn509 trijicon sro pov in action

Better gear doesn't make a better shooter and only high volume practices can.

For pistol red dot shooters, try adjust the grip panel sizes & grip angle so the dot appears in front of your eye every time.

Using A Red Dot While Facing Direct Sunlight

shooting into the sun red dot sight
  • Try to get out of the indirect sunlight as much as possible for better target ID
  • Wear a brimmed hat
  • Up the reticle brightness

See other 4 tips to combat sun glare here

Using A Red Dot In Low Light

holosun hm3x with leupold lco pov

Red dot sights do work at night, however, it works better with a weapon light to identify targets.

  • Readjust the dot brightness for low light home defense application after an outdoor range trip
  • A small 2 MOA dot is better than using a ring style reticle (like the EOTECH) that can cover up the target in low light situations, and making it difficult to see the target sometimes