How Does a Red Dot Magnifier Work?

Red dot sights are overwhelmingly popular sighting systems for firearms, and can be found on anything with a trigger these days, including compact handguns designed for concealed carry.

RDSs boast excellent target acquisition speed and ease-of-use, supreme durability, and increasingly lengthy battery lives that neutralize one of their chief shortcomings, a near total dependence on batteries.

For any kind of close-range work with any kind of firearm, the RDS is hard to beat, but it is not the ideal choice for long range shooting; typically when ranges start to increase past a hundred and fifty yards or so. Used with a rifle you will want some magnification to increase your performance out there.

Red dots can be pushed past the close-range envelope by a skilled shooter in ideal conditions, but generally they start to struggle with long-distance work all around.

But there is a hardware solution for most red dot sights in the form of the red dot magnifier, a small, standalone telescopic attachment that allows you to use your red dot with increased magnification.

These devices are waning in popularity today, but they were all the rage in the latter years of the first decade of the 21st century.

Even so, they are still viable for specific shooters or situations and if you are new to the shooting game you might not be familiar with these optical add-ons.

In today’s article I will explain how red dot magnifiers work and share with you some considerations to help you figure out if one is right for you.

What is a Red Dot Magnifier?

The red dot magnifier, colloquially called just a ‘magnifier’ in gun-centric settings, is nothing more than a small magnifying optical device, a tiny telescope or monocular, one that attaches directly to an existing red dot sight.

It provides a small amount of magnification, typically 3x, but you will find examples of anywhere from 1x all the way up to 6x.

In effect, they function more or less just like any magnifying optic, only they do not have a reticle of their own etched into the lenses. Instead, as you are probably anticipating, the reticle is provided by the red dot sight that is married to.

But aside from this difference they are used and function very much like any other magnifying optic, complete with potential parallax issues, a required eye relief for optimum function and the need to zero many of them.

Any magnifier relies on a separate mounting solution in order to interface with the red dot sight. They are as a rule standalone devices, not built into an RDS.

Effects

Magnifiers magnify what you can see normally when using your RDS. Because ‘duh.’ That’s it. If you are having difficulty seeing your target or establishing a fine point of aim on the far edge of normal RDS ranges, a magnifier will give you that little bit of extra oomph to make the shot.

What’s more, their typical mounting solutions can allow you to quickly engage or disengage the magnifier from its position behind the sight so it is on when you need it, and off when you’re done.

For shooters who desire the ability to engage just a little ways past typical RDS ranges, they are ideal. It is entirely possible to push a red dot sight equipped with an appropriate magnifier out to 200 yards and even beyond depending on how much magnification the magnifier provides.

Considering the current top-end magnification provided by any magnifier is 6x, you aren’t going to get dramatically farther than that on a point target.

If it seems a little kludgy compared to a traditional variable rifle scope, it is, but they do generally work as advertised with a few caveats. Some of these caveats are a big deal, but the benefits might be equally important. We will address them just below.

Pros

• ✅ Adaptable: A red dot magnifier combo prepares shooters for their most likely shooting scenarios, i.e. close range shooting at high speed with high accuracy demands, while also enabling them to make rare but still plausible shots that occur at ranges where an RDS is lackluster.
• ✅ Cost Effective: It is possible to add magnifier capability to virtually any RDS at a later date, meaning you don’t need to miss out on range time or the perks of an enhanced sighting system while you save up for typically expensive magnified rifles copes like an LPVO and the required rings or bases.
• ✅ Lean: A magnifier can be removed from a rifle entirely when it is not needed without hurting the zero of the “host” RDS. This saves weight and space. When used with a quality mount, the magnifier can be reattached with little or no change in zero.

Cons

• ❌ Less Forgiving: A magnifier is inheritor to all the problems and quirks of any magnified scope, namely it has a specific eye-relief and an eye box that might be strict or forgiving, completely eliminating the chief advantage of an RDS while the magnifier is in use.
• ❌ Awkward Mounting: A magnifier will typically be installed via a swing-away mount, flip-to-side mount, or a quick detachable mount using a snap-on mechanism. Other options are screw-in mounts (these mount directly to a threaded body near the eyepiece of the RDS itself) or direct mount which is installed on a semi-permanent basis. All have significant disadvantages. (See section below.)
• ❌ Imprecise: Maybe, see next section. As detailed below you’ll perceive your reticle as being much larger when superimposed on the target when you are using a magnifier with an LED-based RDS. This does not mean they are not usable, or that the performance gain at ranges just beyond where you are comfortable with a sight are not worthwhile, but true extended-range use with a magnifier virtually mandates a holographic sight.

Type of Sight Matters: Holo vs. LED

Here is the real sticky pickle of using a magnifier with your RDS. The magnifier will also magnify the reticle of any LED-based sight, not just the target.

This will be noticeable with a 2 MOA dot, significant with a 4 MOA dot and infuriating with anything larger. The shape of the reticle too can make a big difference. I’ll explain.

For those who are unaware, the size of the reticle in an RDS is measured in MOA, or minutes of angle, and reflects how many inches in diameter it is and how much of the target it will cover at 100 yards (or meters, depending on the sight’s construction).

This is simple enough to understand; a 2 MOA dot covers a 2-inch diameter circle at 100 yards, a 4 MOA dot covers a 4-inch diameter circle at 100, yards and so on.

The same example again at 200 yards; the 2 MOA dot is not 4 inches, the 4 MOA dot is a whopping 8 inches, and anything bigger covers pretty much the entire torso of a man-sized target.

But to your eye, when viewed through the magnifier, the size of the reticle as it appears on your target will be drastically increased, looking enormous, even though the actual size in proportion to your target is the same.

This means that that tiny, fine aiming point you typically perceive when using your RDS will now be a large ball, a generally indistinct aiming point.

Larger reticles (which are a benefit for some) at close range for fast, coarse shooting can cover or even exceed the bounds of your target at extended ranges when viewed through the magnifier.

You might be asking yourself what good is being able to see farther if your reticle is now so imprecise and unwieldy you will have difficulty placing rounds with precision?

What good is an aiming device that is nearly as large as or larger than the target itself? How are you supposed to pick out a refined, precise point of aim with that?!

That, friends, is exactly the issue. Your magnification is now up to the task, but your reticle might be too clumsy depending on its size and the range of the target.

This leads to a variety of workarounds, everything from learning your holds using the top center of the “rim” on the dot, choosing a different reticle like a chevron (which maintains a small aiming point at the peak) and other trickery to overcome this effect.

But there is one elegant solution for this confounding problem, and it is to simply employ a holographic-type sight if you plan on using a magnifier at long range.

I will not bore you with the technical differences between an LED and holographic (laser-based collimator) sight, but suffice it to say those differences mean that the reticle of a holographic sight appears the same size to your eye even under magnification.

Consider the EOTech HWS: Warts and all many shooters love these sights because their reticles are excellent, consisting of a nice big hula-hoop crosshair for close range acquisition and a tiny, fine 1 MOA dot in the middle for precision aiming.

That is nice enough on its own, but used with a magnifier it really excels because you will maintain that tiny, fine 1 MOA dot when used in conjunction with any magnifier! That is a great perk.

Mounts

The mounting systems are my least favorite part of any magnifier. Frankly, most of them are just not very good, offering the unenviable combination of poor placement, imprecise lockup or bulky awkwardness whether the site is in use or not, and they are unfortunately a necessity for the vast majority of magnifiers.

The most popular mounts for RDS magnifiers are so-called flip-to-side or swing-away mounts that as you might expect allow the magnifier to remain mounted but be quickly swung or pivoted to one side or the other of the rifle it is mounted on.

In essence, this allows the shooter to quickly pop the magnifier on when extended range shots present themselves and just as quickly get it back out of the way to use the RDS unobscured.

Most of them do function as described, but they can be expensive, and several varieties exhibit sloppy lockup when the magnifier is in place.

No matter what kind you use, the magnifier will awkwardly and annoyingly be hanging to one side when stowed. This negatively impacts your peripheral vision when aiming through the sight normally, and is prone to tangling and snagging the rest of the time.

A somewhat leaner but no less awkward mount is the quick-attach (or quick-detach) mounting system, where a dedicated base is installed behind the sight and the magnifier is removed entirely to be stowed separately, off of the rifle, until it is needed.

While this definitely helps to keep the rifle lean and light until the magnifier is called for one would need to be in a dedicated position of observation with time and opportunity to attach the magnifier prior to shooting, making it less than ideal for dynamic use.

Still, these mounts are simple, and for those who do not anticipate needing the magnifier in close-quarters, life-threatening situations they do work well.

A rare type of magnifier mounting system is dependent upon the optic itself, and that is the screw-in or thread-on mount.

These magnifiers, as a rule, are manufactured specifically for the optics that employ this mounting system, and many of them are not very good, included with a sight as a bonus feature or tchotchke more than anything else.

Nominally, this should ensure excellent and consistent mounting, but it is very slow and fidgety to put on or take off since the threads are universally very fine on this type of mount.

The last type of magnifier mount is the fixed mount, which is exactly what it sounds like. The magnifier is installed semi-permanently immediately behind the RDS for full-time use.

In many ways this is one of the least attractive mounting options since it completely eliminates one of the chief positives of magnifier use, which is being able to activate it when it is needed and deactivate or remove it when it is not.

If this type of mount is desired, one can make a very strong case for skipping the RDS and magnifier combo in lieu of an LPVO.

Charles’ Take

I have a fair bit of experience with magnifier-equipped RDS sights from some years ago, and they never really gelled with me.

Based on my experience with them in training, practice and competition I was always struck by how tightly defined their optimum range was, no matter which type of magnifier I used.

At most typical RDS ranges, the magnifier would only slow me down, and the need for precision was not so great that it justified clicking into place, establishing proper eye relief and then setting up the shot.

At ranges where I started to feel less confident with my red dot, I was glad to have the magnifier and my position usually justified employing it.

But from there, things started to sour…

I could go another 75 yards, maybe a hundred, beyond that “sweet spot” and still be glad of the magnifier, but much past that the greater perceived size difference in the reticle made precise aiming challenging, meaning I had to slow down even more to establish a finer point of aim on what was in reality an imprecise reticle in that instance.

Was it doable? Absolutely. Can I imagine a situation where I would still be glad to have that capability in a real situation? Yes. But…

But as longer and longer shots present themselves I found myself thinking over and over again “why don’t I just have an LPVO for this?”

With a proper variable scope, I would have even more advantages, namely an extremely precise reticle, adjustable magnification and drastically improved optical quality.

At ranges where the RDS shined on its own I resented the additional bulk and awkwardness of the magnifier. I thought constantly about taking it off entirely.

I will admit that the situation greatly improved when switching to my typical and favorite RDS, an Aimpoint of one kind or another, to a holographic sight, the EOTech.

The far finer reticle of the EOTech that stayed small with the magnifier in use made all the difference on those longer shots. Unfortunately, the unreliable and problem prone EOTech dashed these dreams. I went back to the Aimpoint after a couple of seasons and never looked back.

Other shooters and professionals have different opinions and different experiences with magnifiers. That is fine, you should listen to them, but my perspective is that the magnifier equipped RDS is a “Band-Aid solution” that can help you get just a little bit more range out of your primary sight at the expense of increased bulk and fiddliness.

Is the trade-off worth it? That is up for you to decide based on your usage criteria and objectives. For me, I go all in with an RDS alone and work harder to extend my effective range with it versus relying on a magnifier.

If I anticipate a high likelihood of long-range shots will be working at extended ranges the LPVO is dominant for a reason in our era and that is what I go with.

Ultimately, I believe magnifiers are starting to go to the way of the dodo for a reason: the juice is no longer worth the squeeze except for very specific individuals in very specific circumstances.

Conclusion

The RDS magnifier is an interesting piece of kit that can help you extend the useful range of your primary red dot sight by serving as an add-on telescope.

While definitely useful, these devices come with some not insubstantial flaws and must be approached with dedication and revised practices in order to get the most out of them.

The necessity of additional mounting equipment does add complexity and weight to the host rifle, but if you always find yourself just needing an extra hundred yards or so from your RDS a magnifier might be the perfect solution.