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Primary Arms SLx MD25 Review

Primary Arms offers a number of entry-level rifle scopes and red dot sights. One of the latest models is the Primary Arms SLx MD 25 micro red dot sight. It’s a great medium-sized red dot sight build with good quality and a great feature set.

Review of the Primary Arms SLx MD-25 Red Dot Sight

Primary Arms is a relatively young company that has made huge strides in the riflescopes market with innovative yet affordable optics. Most offered red dots, prism, reflex sights, and rifle scopes, and even red dots on top of scopes, are geared towards entry-level markets. Every iteration and newly introduced product has seen improvements over the previous generation while staying affordable.

Over the years, Primary Arms has introduced high-end optics that are based on their ACSS reticles. One of the latest introductions in the red dot offerings is the Primary Arms SLx MD 25 microdot.

Review of the Primary Arms SLx MD25 Red Dot Sight

The SLx MD25 has, as the name suggests, a 25mm lens with a 2 MOA dot. There’s also an option to get the primary arms SLx MD 25 with Primary Arms’ ACSS reticle calibrated for the 5.56.

It’s a bit larger in build-size than your typical microdot like the Aimpoint T2. Yet, it’s also not a full-sized red dot like the Aimpoint Pro or the Sig Sauer Romeo 5 or 7. You might call it a hybrid that combines a small size with a lot of capabilities.

Don’t be fooled by the small size, though. The Primary Arms SLx MD 25 can easily compete with older 30mm red dot optics, including the Vortex Venom RDS among others. Maybe not with the current generation but certainly with sights that are a few years old.

The 25mm lens is just the right size to either allow to aim through the tube or to look around it. If you aim through the sight, you get a large field of view that is significantly larger than that of your typical microdot optic. Yet, the optic is overall small enough that you can look around it and practically enjoy an unlimited field of view.

Is the Vortex Crossfire red dot sight any good?

Primary Arms SLX MD25

Check out the review of the Tacticon Predator V3 as a viable alternative!

Image Quality and Red Dot Crispness

The glass quality and lenses on the Primary Arms SLx MD 25 are what you expect from a sight in that price range. It does easily compare to higher-priced red dot sights.

The 2 MOA dot itself is crisper than you’d see it on many other sights. Primary Arms did a great design job on the 2 MOA red dot’s quality and crispness.

It does not necessarily compare with the highest-end red dots, but it holds its own against mid-range reflex gunsights. If you combine the sight with a magnifier, then you might get some reduction in image quality, but it’s nothing detrimental. The 2 MOA red dot of the SLx MD 25 stays sharp even when magnified, for example with the Meopta MeoMag 3x red dot magnifier, which cannot be said for many other red dots.

Combine it with a Red Dot Magnifier

You can combine the MD25 optic with a red dot magnifier to get a 3x, 5x, or even 7x magnification to increase the sight’s versatility even further. The sight is also night vision compatible, and you can set it up to be used during night hunts.

It does a surprisingly good job in combination with a NOD. The Primary Arms SLx MD25 works well with night vision, with only a slight reduction of light entering the night vision optics.


Illumination knob on the Primary Arms MD-25

As it is built larger than your typical microdot, you get a larger field of view on the SLx MD25. The larger build also allows for a more extensive adjustment range of windage and election compared to smaller red dot sights with a 20 mm aperture. Elevation and windage can be adjusted in 0.5 MOA click values up to 50 MOA.

The SLx MD 25red dot sight is night vision compatible. The Primary Arms SLx MD 25 has 11 brightness settings, including two settings for night vision use. The knob for the illumination settings is large and placed on the left side of the optics tube. It also acts as the battery compartment, which does explain the size. You might need some getting used to it if you are trying to aim around the MD 25 sight, and the knob is in the way of your line of sight.

You can even use this optic, as well as pretty much any red dot sight when it’s dark around you. Not when it’s pitch black but they provide great visibility during dusk and dawn.

Battery Life

The battery life of the MD 25 red dot sight is rated to be 50,000 hours for the 2 MOA reticle and 12,000 hours for the ACSS reticle. These battery life ratings can be achieved at a medium setting. The long battery life that you specifically get for the 2 MOA reticle makes the SLx MD25 an excellent choice for an ‘always on’ sight for personal defense. – Another great optic for personal defense is the Dagger Defense DDHB RDS.

The knob to set the brightness settings is located on the left side of the sight. It also acts as the battery compartment. The optic requires a CR2032 coin battery that is easily switched out.

Mounting Options

One genuinely nice feature of the SLx MD25 is that you can use Aimpoint T1 style mounts. These are commonly available, and it makes it easier to find a mount that works.

The MD 25 comes with a low base that provides a 0.96″ center-line height and a standard riser to push to 1.41″ center-line height These make it easy to setup the sight for co-witnessing with iron sights. Additionally, there are two more risers to achieve 1.535″ and up to 1.64″ center-line height. These included mounts and risers are of reliable quality and allow to pretty much position the red dot sight however you want and need it.

If you want a quick-detach mount, you can pick any of the large number of Aimpoint T1 style QD mounts. This way, you can move the sight from one rifle to the next without complicated remounting.

Primary Arms SLX MD25 Red Dot Sight

Final Thoughts

The Primary Arms SLx MD25 is a great red dot sight for the price. It offers a lot of features, and the crispness of the 2 MOA dot and the overall image quality is quite impressive.

The size is a solid 25mm, which places it right between the microdots at 20 mm (typically) and the full-size red dots, usually having a 30 mm lens. It’s large enough to provide a wide field of view if you aim through the optic, yet it’s still small enough to aim around it and have an unlimited FOV.

The battery life on the SLx MD 25 with the single dot is a substantial 50,000 hours on medium brightness settings. This makes it a great choice to use for home defense where you want the sight to be on pretty much all the time.

Having the two night vision settings additionally makes it a great choice for any night hunt or tactical deployment. The additional nine brightness settings on the SLx MD 25 allow you to find the dot’s right intensity in pretty much any lighting conditions.

Switching the mounts that come with it and replacing them with any Aimpoint T1 compatible mount is a nice bonus feature. It’ll make it possible to change any of the numerous QD mounts for the Aimpoint optics.

The weight of the sight is 5.4 oz without a mount. If you add 2 or 3 oz for the mount, then you end up with a sturdy and robust red dot sight mounted on your rifle at less than or around 10 oz. Not a featherweight but also not on the heavy side.

All in all, you can’t go wrong with the Primary Arms SLx MD25. It’s a magnificent red dot sight at an affordable price point.

Review of the Primary Arms SLx MD-25 Red Dot Sight
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Tom Devine