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Red Dot Sights

Three types of red dot sights

Red Dot Sights: Everything You Need to Know

Technology has advanced in recent years to give us the kind of digital tools that we’ve only dreamt of before. Invented in the mid-70s and used for anti-aircraft guns during the early 20th century, red dot sighting systems are no exception. Thanks to technological innovation, red dot sights (RDS) have come a long way in the last 40 odd years. They are now clearer and smaller, with more impressive battery life. Overall, the quality of red dot sights has improved to the point where we now have a whole range that includes everything from full-sized rifle optics to smaller optics designed specifically for duty handguns.


While modifications made to traditional iron sighting systems allowed users to see and track their sights, it still didn’t change the way the naked eye sees the sights or target itself. Military and police forces had to rely on a rudimentary front sight, rear sight, and threat targeting system. But that all changed when RDS entered the scene and gave law enforcement personnel a duty-grade sighting system that helped them aim better and was easy to use.


Red dot sights have been used for a long time by competition shooters, but it’s the adoption of RDS by military and police that lead to more advancements and, eventually, to more shooters using these sights.


How they work

Red dot sights are a simple optic that, if you can’t guess, uses a red dot reticle and is designed to be used at close to moderate ranges. Some may be green, but they are still referred to as red dot sights, optics, or red dot optics. Take note that they don’t feature a built-in magnification and, as such, aren’t called scopes.


RDS use a spherical mirror that reflects light coming from an LED on its axis focus. To prevent other light from disrupting the reticle, the spherical mirror has a special coating that only reflects red light. Essentially, this lets you see the reticle through your optic, but someone on the other side won’t be able to.


Traditional sights offer variations in the shape of high viz rings or fiber optics, but this still doesn’t really change how the sights are used. Your eye will still need to align the front sight, rear sight, and target before you can take the shot, meaning there are three focal planes. However, RDS lets you shoot by only using one focal plane: the target. This means that shooters can remain focused on the target while aiming their firearm and, as soon as the dot is aimed over the right area, they can shoot. Of course, less focal planes makes shooting easier, but there’s also a lot of benefit in being able to remain focused on the threat. Because these sighting systems are incredibly easy to use, they are a great tool for training new shooters.


Different kinds of RDS

There are several different kinds of red dot optics that fulfil different purposes and perform differently. The vast majority of red dot sights are tube-based designs made for full sized firearms, called standard rifle optics. These feature a 2-3 MOA (more on that later) red dot with a 25+mm objective lens. They have been designed for close to moderate range shooting and can be used with a magnifier or night vision optic.


You also get miniature red dots, these are the smallest of the small. They have been designed for use on pistols and for use as backup sights. Because these RDS are available in very small sizes, they are a good option for CCW. However, you should keep in mind that “red dot” is a blanket term that describes a wide range of sight systems that project a red reticle on your field of view. Most of the red dot sights on the market today fall within three categories: reflex, prismatic and holographic.


i. Reflex

Short for reflector, these sights use a light-emitting diode (LED) to project the red dot onto a lens that the shooter looks through and are the most common type of RDS. There are two kinds of reflex sights: tube-shaped sights that look like a short riflescope with a contained beam and two lenses with the rear one projecting the aiming point onto the front lens, and small sights with an exposed beam that have an aiming point that is projected from the rear of the sight onto an aiming window. Because these exposed sights only have one small window, the dots themselves are extremely small.

Reflex type red dot sight

ii. Prismatic

These kinds of sights resemble riflescopes but have fewer lenses. Instead of using an LED and reflective lens, prismatic sights use a prism to flip and focus the image you see down the scope. The reticle is etched onto the glass and can also be illuminated, causing them to be referred to as red dot sights. Because prismatic sights use more sophisticated reticles that include bullet drop indicators and ranging information, they can also offer a small magnification with a larger sight picture that reflex sights.

Prismatic type red dot sight

iii. Holographic

Offered by optics manufacturer EOTech, holographic sights or holographic diffraction sights use a laser-transmitted hologram of a reticle. The reticle is recorded in 3D onto a holographic film and is not magnified. Essentially, these sights record the light reflected off an object/scene, decode the recording, then reconstruct the light field in the sight viewing area. Instead of the common tube-style sight design, it uses a rectangular window to offer an excellent field of view and the ability to move your head around without affecting the point of aim. These reticles can be two- or three-dimensional and appear on the target plane.

Holographic type red dot sight

Sizes + MOA (reticle size)

Chart with 3, 6, 8 & 10 MOA

Red dot sizes are measured in minutes-of-angle (MOA) and are controlled by an aperture hole in front of the LED. This is an angular measurement (not a measure of distance) and one MOA is 1/60th of a degree, which translates to 1 inch per 100 yards. A smaller MOA reticle will cover less of targets at greater distances, meaning you will be able to get a more accurate shot at a moderate distance. However, bigger MOA reticles are easier to see and get on target.


Once aligned, the reticle is parallel to the barrel out to infinity. Because bullets rise and fall in a parabolic arc and other factors like temperature and wind affect flight path, the bullet won’t land exactly where the reticle sits on the target. Reticles indicate the point of impact within a defined area around where the reticle is projected. Essentially what this means is that the larger the red dot = the larger the area where the bullet will land. The smaller the red dot = the more precise the shot will be. The smallest dot available is generally 1 MOA. Because a bigger dot is easier to see, yet not as accurate, and a smaller dot gives more precision while sacrificing acquisition, the best size optic is usually between 3 MOA to 4 MOA. This is most common for handguns and gives you a good compromise between precision and acquisition.



Another factor that you need to keep in mind is that RDS are illuminated and, while some systems use passive illumination from fiber and/or tritium optics, many rely on battery. Fiber and tritium optics have the benefit of working in low-light environments, but they’re not as bright as those powered by batteries. With battery operated red dot sights that typically use an LED, you are able to adjust their brightness. This fine tunes visibility and clarity, but brings in another element to consider: battery life.


Battery life depends on the make and model, but are also affected by your settings. Think of it the same as your phone - the higher the brightness on your screen, the faster the battery drains. That being said, RDS boast significantly more impressive battery life than smartphones. Some models like the Aimpoint Acro C-1 can last up to 1.5 years with the right batteries. However, there are handguns like the Springfield Hellcat 9mm (link to Springfield blog) that provide iron sights that co-witness with red dots in case of dead battery or sight failure.


If you’re using red dot sights on your carry gun and anticipate low-light environments, you will naturally want optics with a longer battery life. Look for something that has an auto-dimming capability and, if brightness needs to be adjusted manually, consider whether you will be able to do so discreetly from your carry position. Also consider where the battery is located. For some kinds, you’ll need to remove the optic off the mounting plate while others have top-loading battery compartments that are generally more convenient.

RDS Pros

● Incredibly simple: easy to use, easy to get and stay on target.

● Fast sight acquisition to put accurate rounds on target from a low ready position.

● Increased accuracy at less than perfect angles.

● Interchangeability between weapons.

● Options for magnified and non-magnified red dot sights.

● Options for battery-operated and sights that don’t require batteries.

● Reflex and holographic sights can be used with both eyes open.

● Because of the wide range, there are entry level affordable RDS as well as higher quality and more expensive sights.

RDS Cons

● Cons are dependent on the type of red dot sight.

● Prism sights have a smaller eye relief, so your eye needs to be close to the scope.

● Reflex sights don’t offer magnification.

● Holographic sights are expensive.

● Need to have your slide milled for a red dot optic.

● Risk of sight failure or dead battery in an emergency.

● Need a good draw and proper presentation from a holster to see the dot, which may require additional training for some.

Rene Aguirre

Rene Aguirre is the founder and owner of Bravo Concealment. Rene has been carrying concealed on a daily basis for over 8 years and has been a CHL (concealed handgun license) holder for more than 20 years. Finding a high interest in firearms for many years, Rene started Bravo because of the “lack of” a good concealed carry holster.

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