Primary Arms SLx MD-25 by Jeremy S. for TTAG
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The landscape of “budget” optics has sure changed over the last decade or so, with many new companies producing ever better, higher-quality options at affordable prices. Primary Arms is one of those brands that has established itself and earned a firm foothold in the market by bringing good looking, perfectly serviceable, often quite feature-rich optics to the masses. One of the latest is this SLx MD-25 Microdot, and it’s pretty darn great.

Jeremy S. for TTAG

Included in the box with the SLx MD-25 is a low base (seen on its own to the right in the photo above), a standard riser for centered/absolute co-witness with typical AR-15 sights (seen above installed on the optic), and two spacers: thick and thin (not pictured). The thin spacer provides a 1.535-inch height to center, which I believe is Aimpoint’s standard height, and the thick spacer nets a 1.64-inch height for that lower 1/3 alignment of your iron sights.

Along with the mounts and spacers is the necessary hardware for each available option. While most optics would have you purchase mounts separately, the MD-25 comes with every conceivable option right in the box. Plus tools, a cleaning cloth, and a user manual.

Quite the comprehensive kit for its very reasonable $169.99 MSRP. If you’re lucky enough to pounce when one’s available, there are sometimes even open box and blem units available for about $40 less. Either way it’s a heck of a deal.

Mounts, by the way, match the Aimpoint Micro (T1/T2) pattern so there are lots of other options out there in case you want to go QD or otherwise get fancy.

Jeremy S. for TTAG

You may have noticed that the SLx MD-25 isn’t a typical microdot. Rather, it occupies approximately the standard footprint of a microdot but in a larger diameter format.

Jeremy S. for TTAG

At the expense of weighing in about 2 ounces heavier than a similar-sized microdot, it provides the large field of view of a 30mm, full-size red dot scope but does so in a smaller, lighter package than what you’d find in that category.

Jeremy S. for TTAG

Rotating the left-side knob in either direction clicks between 11 brightness settings, including two night vision-compatible levels, plus “off.”

The MD-25’s single CR2032 battery resides within this knob, and the sight will run 50,000 hours off that single battery (at medium brightness). That’s pretty awesome. That’s 5.7 years. From a $1 battery (if you pay for a nice one).

Also visible in the photo above, the inside of the MD-25’s ocular bell is threaded to accept flash hiders or other caps.

SLx MD-25 courtesy Primary Arms catalog

Under the nicely knurled elevation and windage turret caps are easy-to-adjust turrets with clean, crisp, audible, half-MOA clicks with 50 total minutes of adjustment each. The rectangular bar on the top of each cap can be used as a tool to turn the turrets, but you aren’t likely to need it as the turrets themselves are serrated along the edges and easy enough to rotate by hand.

Courtesy Black Collar Arms

Thanks in a big part to the easily swappable mounts, the Primary Arms SLx MD-25 immediately found a home in my testing rotation. Within the first month I had run it with the low mount on a few of our Pork Sword Pistols in various calibers.

Jeremy S. for TTAG

I had run it low mounted on a Radical Firearms RF/22 during the Franklin Armory 22-C1 Binary Trigger review.

Jeremy S. for TTAG

I ran it on AR platforms in .22 LR, 9mm, 5.56, and 300 Blackout. Including machine gun use:

In all cases the MD-25 was just what the doctor ordered. It has a crisp 2 MOA dot (it would just cover a 2-inch diameter target that’s 100 yards away) with a full brightness range appropriate for use from dusk to dawn, including in the full Texas sun where many dots really struggle to show up.

Note that in the fourth photo in this review — the one that shows the dot — 95% of that “starburst” look to the dot and the reflection inside the edges of the optic is something I couldn’t prevent my camera from showing, but it’s an effect of the camera, not actually something your eye sees in the optic. Unless you’re in a fairly dark environment running the red dot cranked up to 11, the MD-25 has about as nice and clean of a precise little red dot as they come.

Jeremy S. for TTAG

While fully multi-coated, the SLx MD-25’s lenses impart far less color shift than most red dots and provide a nearly neutral, clear view that’s much closer to naked eye vision than the norm.

Side note: I’m wearing the same hat and t-shirt in both videos and in the photo above, yet all were taken not just on different days but in different months. I clearly need to expand my wardrobe.

Courtesy Black Collar Arms

Speaking of wardrobes, the SLx MD-25 is pretty enough for any occasion. It has that high-end look to it with an appealing design, clean machining, and an even, deep, hardcoat anodized finish.

Jeremy S. for TTAG

Over many months of regular use on all sorts of different firearms, the MD-25 has been a rockstar for me. It retains zero without fail (and has even proven its ability to return to zero after removing it and later returning it to the same gun), has a precise enough dot for accurate shooting out to a couple hundred yards, is daylight bright even in full Texas sun on a light background, provides a very wide field of view with nearly no color shift, and comes right out of the box with all of the mounting options necessary to work on just about any firearm.

The Primary Arms SLx MD-25 is a no-brainer, solid choice for a fantastic red dot at a killer price.

Specifications: Primary Arms SLx MD-25 Microdot

Reticle: 2 MOA Dot
Brightness: 11 settings (including two night vision) plus “off”
Dot Color: Red
Click Value: 1/2 MOA
Adjustment Range: 50 MOA
Battery Life: 50,000 hours at medium brightness
Battery Type: CR2032
Material: Aluminum
Finish: Hardcoat anodized
Weight: 6.5 ounces
Warranty: Lifetime
MSRP: $169.99

Ratings (out of five stars):

Utility  * * * * *
When you combine two mounts, two spacers, plus all the hardware and tools necessary right in the box with a 2 MOA dot, wide-field-of-view optic you nail five-star utility.

Form Factor  * * * * 
Good looks with excellent machining and finish. It looks nicer than its MSRP would suggest.

Optics  * * * * *
Clear glass and a crisp, stop sign red dot with plenty of brightness adjustment. At this price point the optics quality is five stars for sure.

Durability  * * * * *
While I didn’t torture test the MD-25, others have and it’s clearly a stout, well-made optic. In my testing I found the turrets to track true and the zero retention was flawless. All components appear well-made and everything fits and functions correctly and confidently.

Overall  * * * * *
I simply have no gripes or nit-picks to level at the SLx MD-25. While, sure, I could request enhancements such as “off” clicks between each of the brightness settings, a QD mount(s), or flip-up lens caps, at an MSRP of just $169.99 I’m fully five-stars happy with this fantastic, large diameter microdot.


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  1. Battery cover and turret covers are too bulky at this point and represent an unacceptable amount of visual clutter from the operators standpoint. I’ll stick with something like the rheostat operated holosuns, thank you.

  2. “…is daylight bright even in full Texas sun on a light background….”

    I was stationed at Ft. Hood twice. that’s pretty bright. I have a Sig Romeo on my Ruger PC, but I’ll look at this one as I have something new that it could sit on. About the same price as the sig if not on sale.

    Thanks for review.

  3. “Note that in the fourth photo in this review — the one that shows the dot — 95% of that “starburst” look to the dot and the reflection inside the edges of the optic is something I couldn’t prevent my camera from showing, but it’s an effect of the camera, not actually something your eye sees in the optic.”

    Interesting, my newly re-manufactured eyes do the same thing with point sources of light at night. The same ‘starburst’ effect.

    Anyways –

    The important question is, who’s the attractive Black Collar Arms model in the last picture, Mrs. S? And if so, what’s she doing with a guy like you? 😉

    • Yeah, eyes will do that in the correct conditions. Mostly that’s a dot that’s a few settings too bright for the environment or it’s astigmatism.

      No, that isn’t Mrs S. She’s a local model who’s a friend of a friend and was cool enough to help out with our little private jet photoshoot.

  4. i like this style of optic. have a few of the “other” (cheaper, not pa) 25 series on things from pellet to magnum.
    i’d certainly consider this or the sigs, although the larger portal here is attractive.

    • No need to hide it. The Bushnell TRS-25 pretty much set the standard for (bulletproof?) low cost red dots. There is a reason Bushnell is still manufacturing/selling it today even though Bushnell has moved onto the newer model TRS-26. Granted, the 25 model is getting to be a little old compared to most newer stuff coming out. I have had 2 of the model TRS-25. One on my 5.56 AR that I traded to a friend when I decided to go with a scope. The other is still on my 9mm AR attached with a cheap UTG QD mount. It runs like a champ. Pop it off…put it back on…it still easily whacks 6″ steel at 75+ yards with no adjustments.

      That said, this Primary Arms MD-25 is definitely enticing with the larger field of view. And as doesky2 stated below, if they could make the ACSS reticle work on the MD-25…Primary Arms can just take my wallet.

      • Totally. I also had two TRS-25 for many many years and used them on all sorts of guns. The MD-25 here is definitely newer and upgraded in various ways, from battery life to much larger field of view with significantly clearer, brighter glass. Looking through this is far closer to just having a red dot superimposed on your normal, naked-eye view of the world whereas the older, budget stuff is kind of like looking through the bottom of a tinted glass of water haha.

      • I mounted a TRS-25 on my Ruger 10-22 that came with an optics rail. It is a blast to shoot on a reactive steel target range from a standing position. With Winchester Ultra-speed ammo it will flip the dueling tree small disks at about 40 yards.

        The image is rather tinted. Also, it bothers me some the nobody wants to talk about parallax errors these days. The Bushnell is inexpensive and works well enough, though I don’t think it is particularly good with respect to parallax error. I always try to center the dot in the window to minimize those errors.

  5. Sure wish it had an outside circle also in the reticle.
    After a Holosun 503 I told myself I’d never buy a simple dot reticle again.
    Hurry up PA and give us a circle/dot or better yet an ACSS version.

  6. How does this compare in use to the STNGR Axiom red dot?

    Looks like the STNGR is a little bit shorter and a few ounces lighter with the same battery life. It also comes with low and high mounts and has a quick detact high mount in the box for $115 MSRP.

    I’ve owned PA optics before with no issues, but the Axiom has my eye, but is out of stock right now.

  7. i have a primary arms 1-4x
    right now its mounted on a 16 inch 7.62×39 ar build
    its been on a bunch of my builds
    i like it
    having said that for what they want for this id probably go for the vortex crossfire

  8. I’ve had mine for a few months now and love it. Would have liked to have seen a auto on/off feature like the similar priced sig Romeo 5 but overall a great optic.

    • I do like that feature. PA basically suggests that, for a defensive use gun, you just permanently leave this dot on. Since the battery will go 5.7 years on setting 6 you could just leave it there and swap the battery every few years and call it good haha.

  9. Maybe I read to fast and didn’t see it, but what is the country of origin? If China I’ll pass, I don’t care how good it is.

  10. I downloaded the manual for this unit, and they do say that there is alternate version that has an ACSS reticle. I believe this is a circle-chevron reticle, though I didn’t see any picture of the exact reticle.

  11. I have two of their Primary Arms SLx Advanced Rotary Knob Microdot Red Dot Sights and a Primary Arms SLx Compact 1×20 Prism Scope – ACSS-Cyclops. The Red Dot’s are easily a match if not a win over my sig Romeo 5. Combine that with an automatic 10% discount for all Primary Arms branded products for Veterans if you register with them, and they really can’t be beat. The Prism Optics are really incredible. The best part about Primary Arms is they literally ship within an hour or two of placing an order, and your items arrive days sooner than expected. I am always amazed how fast they get things to me. They produce quality products they stand behind at a great price and they provide incredible service. What more can you ask for?

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