What is a RMR Sight?

Many of us are old enough to remember when iron sights ruled the day. Optics were never fully depended on because they could fog up, break, or simply stop working due to Gremlins in the mechanism.

Optics have become more durable and dependable than ever. But what about optics on handguns? We are witnessing the same, slow process of optics gradually being accepted onto pistols that we witnessed with rifle adoption two decades ago. What started as an edgy experiment with competitors is now becoming fairly common practice among the military, savvy concealed carriers, and law enforcement.

So, what is a RMR sight? These optics are called a number of things: RMR (Rugged Miniature Reflex), RDOs (Red Dot Optics), MROs (Micro Red Dots), RDS (Red Dot Sights). Though they have a lot of names, we’ll call them RMRs throughout…and the names all mean essentially the same thing, anyway. Simplified, an RMR is a metal or plastic frame housing a piece of glass onto which a red dot is projected. All the shooter has to do is look at the target, place the dot on it, and fire. The shooter no longer has to align a front sight, a rear sight, and a target. Where the dot is, the bullet goes, simple as that.

This blog is going to talk about what an RMR sight is, how it helps the shooter, and what some of the advantages and disadvantages might be. We’ll talk about some different features out there and what to look for if you’re in the market for an RMR.

Advantages + Disadvantages of RMR Sights 

Again, an RMR sight is a metal or plastic frame, housing a glass lens. There is a bit more to it than that; there’s also the base that attached to the firearm. This base contains the mechanism that projects the dot onto the lens. It also contains the adjustment mechanism, allowing you to zero the optic. Since these optics don’t run on sunshine and rainbows (wait…some of them do, but more on that later) the base also holds the battery.

The battery powers the mechanism that project the reticle onto the lens. It does so by lighting an LED. The light from the LED is fired through a mirror which projects it up onto the lens. The lens is transparent, allowing the shooter to see both the target and the red dot.

The advantages of a RMR are many. First, you only have to line up two objects in your field of view – the dot and the target – rather than three as you do with traditional iron sights. This speeds target acquisition greatly. Second, red dots offer a wide field of view and are very amendable to both-eyes-open style of shooting. An RMR can greatly improve accuracy at distance, especially 15 yards and beyond where the dot is a much more precise point than the top of an iron sight. And of course, an RMR can be extremely fast in skilled hands.

RMRs also have some disadvantages. They are battery operated and batteries can fail, especially in cold weather, or when the optics are operated long-term at max intensity. Even under ideal conditions battery life is always a concern. Optics can also become fogged when going from air-conditioned climates to hot, humid outdoors. One problem that can be found with red dot optics is the accumulation of dust on the lens that, over time, reduces the light transmitted through the lens.

And of course, there is also the disadvantage of use commonly observed in those with a deep body of experience with iron sights. This is the classic “looking for the dot” phenomenon. Shooters transitioning to RMR-type optics often have a hard time seeing the dot in the window. While it can be overcome, this takes some training and deliberate practice to overcome. You shouldn’t bolt on a RMR, zero it, and consider yourself good. As with any new tool or technique, training is required to reach competency!

Types of RMR Sights

There are many different brands of red-dot optics on the market. There are two major classifications that we should discuss before going further: standard format and small format. The standard format is the standard for full-size pistols and includes the Burris Fastfire, the standard Trijicon RMR, and the Vortex Venom. Small format (sometimes known as the RMSc footprint) is for compact pistols like the P365, Shield Plus, and Glock 48. Optics in this category include the Shield SMSc, Sig Sauer Romeo, Trijicon RMR CC, and Holosun 507K.

Reticle Options: These optics come with a variety of reticle options. The first differentiator is color. Most feature a red dot, but some are available with a green dot, and the choice largely boils down to personal preference. Many reticles feature a simple, red dot, usually somewhere between 3 and 6 MOA in size (3 MOA dot meaning it would cover 3 inches at 100 yards). Some come with more complex reticles.

Fixed vs. Adjustable Brightness: Most optics on the market have adjustable brightness level, but they don’t all work the same. Some will adjust the brightness level automatically based on lighting conditions, while others require manual adjustment. This is a pretty big deal because an optic that is visible in dim, indoor light will be completely washed out outside in full sunlight. Alternatively, an optic with brightness dialed up for outdoor work will be so bright that you can’t see through the lens in darkness. Adjustable brightness will take care of this automatically, but at a much higher price-point.

Other Features

There are a handful of other really cool features that you should be aware of. You may want some of these…or you may not, but it’s good to know they’re out there.

Shake and wake: This is a battery life conserving feature that lets the optic “go to sleep” when not in use. After a period of no movement the optic will turn off and turn back on when movement is detected. The movement sensors are very sensitive, and the optic will stay on while you are carrying the gun and moving around with it. Again, this feature is one that you can expect to pay more for.

Solar Charging: Alluded to earlier, some optics have a small, built-in solar panel that keeps them charged when are out in the sun. This is a fairly new feature and one that isn’t on many red dot optics, but it shows promise and is worth mentioning. All optics are dependent on batteries, but this at least helps to relive that dependency on battery life a bit.

How to Use a Red Dot Sight

Before we delve in too far, here, there is one point of clarification we should make. The term “RMR” refers to a specific product, the Trijicon RMR, an exemplary product in its class. It is widely accepted as the gold standard of pistol optics. Be aware that if you are purchasing a firearm for a red dot, you will need a mounting plate for that particular red dot, though the terminology is somewhat generic.

Pistol red dots don't mount to picatinny rails like rifle red dots. To mount an RMR type optic, your slide will need to be cut for that optic. Many factory guns now have this feature, like the Glock MOS family of pistols. This means that a portion of the slide is milled out to accept the optic. If mounting a standard-format red dot, you will need a mounting plate – a plate that attaches to the gun and has the appropriate screw patterns for the particular sight. Small, RMSc footprint optics all have the same screw pattern and mount directly to the gun without the need for a mounting plate. The term RMSc comes from a specific optic, the Shield Arms RMSc, widely considered the gold standard of the small-format optical sight.

When mounting an RMR you should make sure the mounting surface (whether plate or directly to the slide) is clean. Thread locker is imperative as it will keep the screws from backing out and ruining the zero. It is important to tighten screws to their recommended torque. Screws that are too loose may allow the optic to move, making a consistent zero nearly impossible to achieve.

Zeroing a RMR is intuitive and easy. You should choose the distance at which you want to zero it – typically 25 yards or so with a pistol. Make sure you are shooting from a rest; with the ammunition you want zeroed (i.e., carry or duty ammo). All red dot optics provide instructions on how to make adjustments to point of impact, and most simply involve turning clearly marked screws.

Applications of RMR Sights

Though new and slowly gaining acceptance RMR sights are here to stay. The benefits are being widely recognized and become more recognized every day as more and more guns ship with an optic included. The applications for these tools are nearly infinite.

Personal defense and home protection is a huge market for RMR sights. They can be incredibly fast, are new-shooter-friendly, and can yield fantastic accuracy. Those in the shooting sports were some of the original innovators using these tools, and that use is only growing.

RMR Sights: An Overview

The modern family of RMR sights offer some incredible advantages in speed, accuracy, target acquisition, and usability. They aren’t perfect and are still battery dependent and susceptible to dirt and fog, but they are pretty amazing. Also, depending on lighting conditions the brightness level may not be bright enough to render the dot visible. One option we haven’t yet discussed is use with co-witnessed iron sights, something we’ve written about before. This provides a fail-safe; in the event the optic fails the shooter has irons instantly available. Suppressor-height sights allow the sights to clear the base of the RMR for a lower-third, or full co-witness, something we feel is prudent if your life is on the line.

If you need suppressor sights to co-witness with your red dot, or have decided you’ll stick with irons, check out XS sights. We offer the best, brightest, fastest sights on the market.