TFB Review: Primary Arms SLx MD-25 Red Dot Sight

    Primary Arms red dots are some of the most popular entry-level optics in the industry. They have come out with a new sight for their SLx line of red dots. The SLx MD-25 is a 25mm microdot that is budget-friendly but offers a great field of view compared to their other micro red dots and some of the competition.

    It Says 25mm But It’s More Like 30mm

    The SLx MD-25 has a full 25mm clear aperture. And it actually offers a wider field of view compared to older 30mm red dots while being smaller and lighter weight. The MD-25 shares some similarities with other micro red dots. However, the power/brightness knob is on the left-hand side. It features a high efficiency LED that offers a run time of 50,000 hours at a medium setting. There are 11 brightness settings with two of them for night vision use.

    MD-25 left side power knob

    The MD-25 currently has a 2 MOA dot but later this summer Primary Arms will be coming out with a version that has an ACSS 5.56 reticle. However, the ACSS version will only have a 12k hour runtime. The MD-25 is compatible with Aimpoint T1 style mounts. As you can see in the photos above and below, I have the MD-25 mounted to an Unity Tactical FAST mount. You will notice a slight shift in height when paired with the Unity Tactical FAST magnifier mount.

    The MD-25 is larger in diameter so a bigger circle sitting on the same plane will be taller than a smaller circle. Below is the original setup designed by Unity Tactical. Aimpoint T2 with a magnifier all on their mounts. Everything lines up.


    Here is a photo of an Aimpoint T2 on the Unity Fast mount and the MD-25 on the Midwest Industries night vision tall mount which is the same height as the Unity Tactical mount. See how much taller the MD-25 is?


    Even though the magnifier looks like it is too low, there is no issue with the sight picture. It is clean and clear.

    How Is The Sight Picture Of The MD-25?

    This is the main issue right? Well the MD-25 is just like any regular red dot. I will be honest, I am not really seeing the larger FOV being that significant. Instead I see the giant power knob on the left side of the housing.

    Below is a side by side comparison of the MD-25 next to an Aimpoint T2.

    Here is a test I did. I mounted a receiver using my tripod and mounted my iPhone to the rail using a Nexus Outdoor adapter. This way the camera and receiver are in a fixed position to a Weapon Outfitter poster. Then I attached the MD-25 and T2 at the same position on the top rail. You can see more of the Weapon Outfitter model’s head in the MD-25 but notice how much of the sight picture is obscured by the windage and power knob.

    Now here is the Aimpoint T2. You see slightly less of the model’s head but you can see a lot more outside of the T2 housing.

    What About Passive Shooting With NODs?

    As many of you know me by now, I have a thing for night vision. If I am going to test an optic, I will test how well it works with night vision.

    I was surprised how well the Primary Arms magnifier worked with night vision. As expected, it does reduce the amount of light entering my night vision but I can easily throw some IR light downrange. Not ideal if you are trying to stay passive but shooting magnified optics without a clip-on is always a struggle. The generous eyebox makes it easier to line up my night vision goggles and get a sight picture.

    SLX MD-25 Final Thoughts

    The larger size is compelling but in actual use, I did not really see a significant difference in the inner diameter of the glass. If I want wider FOV I would switch to a Leupold LCO, Eotech or one of a Machine Gun Optic.

    Yes, the MD-25 is larger but not earth-shatteringly so.

    The power knob being on the left side of the housing is a bit odd, but if you shoot both eyes open then it is not really an issue. The truly attractive aspect of the MD-25 is the price. It retails for $169.99. It has 11 brightness settings and two of them are for night vision. The battery life is really good at 50k hours when set on medium brightness. The MD-25 comes with a standard riser which gives you 1.41″ height. You also get two spacers and a low base so you can get an optic height of 0.96″, 1.535″ or 1.64″ depending on how you mix and match the spacers and riser. It is compatible with most T1/T2 optic mounts although be careful some might not work. Like the ALG 6 Second Mount won’t work since the length of the MD-25 is too long and will interfere with the mount. The optic weighs 5.4 oz without any mount. With the tall Midwest Industries mount, it weighs 8.1 oz. For more information go to theĀ Primary Arms website.

    Nicholas C

    Steadicam Gun Operator
    Night Vision & Thermal Aficionado
    Flashlight/Laser Enthusiast
    USPSA competitor

    Any questions please email him at [email protected]