how to choose a Red Dot Sight for AR-15

These types of sights feature an illuminated "red dot" that functions as an accurate aim point for the operator. A red-dot sight is primarily meant for targets within 100 yards, but it can also work for longer ranges.

How Does a Red-Dot Sight Work?

The red dot sight is often known as a reflex sight, which is a term stemming from the fact that red dots rely on non-magnifying reflectors to display the red dot. Basically, a small LED generates a colored dot of light, which reflects against a small spherical mirror. The mirror focuses the dot onto a lens, which is what you see when you look through the sight. 

On more advanced (and expensive) red-dot sights, additional lenses are added to the setup. The purpose of the lenses are to eliminate "parallax"? What is parallax? It refers to changes in the position of the dot when you look at it from different angles. 

For example - you put your gun in a vise with the red-dot sighted right on your target's bulls-eye. When if you move your head to a different angle and look through the sight, is the dot still on the bulls-eye? Hopefully the answer is yes - that means that your red-dot is "parallax-free". This enhances the overall accuracy and usability of the sight. But be prepared to pay a little extra for a truly parallax-free sight!

Different Types of Red-dot Sights

Red-dots come in many shapes and sizes. "Tube" style sights look a lot like a scope, while "open" style sights are more of a square shape (Eotech sights are a good example of this).

The dot size, dot pattern, and dot color are some of the important considerations in choosing the right red-dot sight for you. You are the operator so your eyes, usage, the mission package and the configuration of your AR-15 would come into play in choosing your red-dot sight.

The dot size should be big enough for you to easily see, but not too large to obscure targets. Dot size is typically meaured in MOA ("minutes of angle"). Essentially, 1 MOA means roughly 1" at 100 yards. So if you have a 5 MOA dot, that means this dot covers a 5" area on a target 100 yards away. For a general use AR-15 sight, we recommend MOA around 5 which covers most shooting situations.

The dot pattern (AKA the reticle) is largely personal preference. Most sights have a dot (hence the name red-dot), but you can also get reticles shaped like crosshairs, or many other patterns. Some sights have adjustable reticles, and allow you to quickly switch between different reticle styles. 

The last main choice is the color of the dot.

Wait - it's a red dot scope so the dot is going to be red, right?

Not necessarily - green and blue are also quite popular. From our experience, blue is often the easiest to see in bright-light condition, and red is best for low-light situations. It's best to try a couple of different sights and see what you prefer. 

Scopes vs Red-dot Sights for AR-15

For a sight that works well on shorter-range shooting (less than 300 yards), the red-dot sight can be a great choice. They typically weigh less than a scope and are much better for quick target acquisition. Also, there will be no "tube effect" that is typical with a scope (due to the varying eye relief on scopes). Basically, a red-dot is much simpler to use but lacks the magnification of a scope. 

One option is also to get a flip-up magnifier that goes behind your red dot, which allows you to quickly magnify your red dot for long distance shots. Despite that added weight, this is a versatile option that is worth looking into.

Perhaps the biggest downside of a red-dot sight is that it requires batteries. No batteries, no dot! But on most red-dots, batteries last so long it's not an issue. For example, on the Aimpoint Micro T-1, the estimated battery life is 5 years!

Best Red-dot Sights for AR-15

There are many choices available for red-dots, and everyone seems to have an opinion on the best reflex sight for AR15. But we have 3 recommendations: Best Overall, Most Indestructible Red Dot Sight, and Best Budget Red Dot.

Best Overall Red Dot Sight for AR-15: Eotech Holographic Red Dot Sights

EOTech is a premier manufacturer of Holographic Red Dot Sights that allow heads-up, 2-eyes-open shooting. EOTech sights come in many different styles and reticles, some of which are made for specific calibers like .223, .308, and .300 Blackout.

What makes the EOTech sights so great? For one, they are reliable - these sights are used extensively in combat and law enforcement. They also have excellent parallax-free optics, and unique rectangle-shaped lenses for a wide field of view. Many of the EOTech red-dot sights are also night-vision compatible, and they are the perfect size for mounting on an AR15 flat-top.

The range of the Eotech sights can be extended through the use of the G33 3X magnifier - a unique "slap-to-side" magnifier that can be quickly deployed for longer distance engagements.

You simply can't go wrong with an EOTech red-dot sight, and for that reason they are our top pick overall.

Most Indestructible Red-Dot Sight for AR-15: The Aimpoint Micro T-1 Red Dot

Aimpoint is a Swedish optics company that makes red dot sights for civilian, police and military use. It is Aimpoint’s belief that a weapon sight should simplify aiming while performing reliably under the toughest conditions. And they most certainly succeed in that. 

While the Aimpoint Micro T-1 is a little more "plain" than the EOTech sights, they make up for it sheer toughness and reliability.

There are 3 things that really stand out about the Micro T-1:

• Battery life - Over 5 years (yes, 5 years!)
• Light weight - Under 4 oz - including the mount
• Durabilty - Extruded aluminum casing and a patended integral picatinny mount that absorbs recoil with no chance of movement

Best Value Red-Dot Sight for AR-15: The Bushnell TRS-25 Red Dot Sight with HiRise Mount

Want a great red-dot sight on a budget? The Bushnell TRS-25 is the best choice for a red-dot sight under $200. Think of this sight as the Aimpoint's little brother - tough, fairly lightweight, and easy to use, and about 30% less expensive. It's not quite to the standard of the EOTech or Aimpoint sights, but it is more than good enough for home defense or casual users.

One of the best features of the Bushnell TRS-25 is the included HiRise mount. This mount raises the sight up a little higher, which puts it in just the right spot for a flat-top AR 15 red dot sight. Also, at about 6oz, it's a small, lightweight sight you'll barely notice when carrying your weapon.