Home » Red Dot Sights » Primary Arms SLx MD-25 Gen II Microdot Review [HANDS ON]

Primary Arms SLx MD-25 Gen II Microdot Review [HANDS ON]

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Primary Arms outfitted the new SLx MD-25 red dot sight with AutoLive.

Paired with the ACSS-CQB reticle, it’s a amazing red dot sight that offers wide-ranging benefits for a shooter that wants it all.

Image by Tina Fa'apoi (Own Work) for Target Tamers

To provide a comprehensive Primary Arms SLx MD-25 Gen II review, I focused on the main acss cqb reticle features that set it apart from alternative red dots.

My hands-on testing criteria included reticle, build, illumination, and battery runtime comparisons.

I get down to the nitty-gritty in my tell-all field test!

My Primary Arms SLx MD-25 G2 Review

Quick Overview...

What I Like: AutoLive technology

What I Don’t Like: Battery life

Best Uses: CQB, Long Range, Small to Heavy Calibers, Target Shooting, Possible Law Enforcement, Possible Home Defense, SHTF

  • Magnification: 1x
  • Coatings: FMC
  • Reticle: ACSS CQB
  • Adjustments: 0.5 MOA
  • Battery Life: 12,000 hours
  • Dimensions: 3” (L) / 6.5 oz
  • Mount: Multi-height mounting system

My Verdict: Overall, the Primary Arms SLx MD-25 Gen II is a genuine do-it-all compact red dot sight. With the ACSS-CQB reticle, it makes for fast close-range work but also features 1 MOA dots for long range engagements. Coupled with a magnifier, I don’t think there’s anything the new MD-25 can’t do.

Why Trust Me?

After hundreds of hours of hand-testing red dot sights in the field and on the hunt, and thousands more hours researching, writing, photographing and creating videos about them, I feel I have earned the title of expert when it comes to optics!

Optics are not just my passion, but also my full-time job!

I get my hands on as many of the optics I test as possible (through buying, borrowing or begging!) and run them through their paces to make sure they will perform out in field.

Check out our optics testing process here.

Over a decade of experience target shooting, CQB and long range has been integral in putting together this Primary Arms SLx MD-25 Gen II Microdot review.

Who is the Primary Arms SLx MD-25 Gen II Best Suited to?

PA MD25 box opening
Box opening - Image by Tina Fa'apoi (Own Work) for Target Tamers

The Primary Arms SLx MD-25 G2 red dot sight with AutoLive has more than a few things in its favor, namely, the AutoLive feature, the ACSS-CQB reticle, and the ‘super-size’ theme it has going on.

It adequately competes against Holosun’s Shake Awake and Sig Sauer’s MOTAC with the AutoLive motion sensor technology. The ACSS reticle can be compared to the field-tested Holosun speed ring and EOTech donut of death reticles. It's bigger than most enclosed micro red dot sights but still smaller than full-size red dot sights like my field-tested Vortex Strikefire II.  

With these combined features, it’s a legit competitor as a high-performing but affordable optic that has it all. Those looking for a red dot for CQB to long-range work, duty rifle, SHTF rifles, and home defense will find value in the new PA MD-25 Gen II RDS.

How Does the Primary Arms SLx MD-25 Gen II Perform?

Tina shooting the PA MD25 RDS
Image by Tina Fa'apoi (Own Work) for Target Tamers

The optics are very good in the PA SLx MD-25 red dot sight. You can see the dichroic coating as evident by the blue tint that is very visible every now and then depending on the light conditions and such. As a result, dot visibility is rarely a problem.

observation with the MD25 collage
Visible blue tint & digiscoping rig - Image by Tina Fa'apoi (Own Work) for Target Tamers

When shooting with the PA red dot, the blue tint wasn’t really an issue for me – or at least I didn't notice it then. Of course, it’s discernible and affects color fidelity when you’re observing or digiscoping with it – but that’s not really its purpose now is it?

Though I’m far-sighted, I still experience similar dot distortion to those with astigmatism. I’m really pleased that I didn’t need my glasses with the SLx MD-25 reflex red dot sight at all. In fact, when I did put my glasses on, the reticle was blurry.

Shooting to 200 yards with PA MD25
Context pic of 200-yard target (left) Target (center) With 3x magnifier (right) - Image by Tina Fa'apoi (Own Work) for Target Tamers

At 200 yards, I did find it a little harder to precisely hold over because the underside of the chevron point was my 200-yard mark for 5.56 rounds. Honestly, I just used the chevron as my aiming point with no real precision on a 15x15” steel plate - I was chasing pings not groups. Hearing every impact provides instant happiness, and in my book, it was a good day at the range.

The reticle itself does seem very small. For me, it would take considerable time to concentrate for precision beyond 200 yards. This is where I pull out one of my favorite red dot magnifiers and it makes a big difference.

Sighting in the red dot for 100 yards was simple. The turrets are very tactile in both directions – no softness or slop. They’re audible too, and you can still hear them with ear protection on. Adjustments are in 0.5 MOA, and they track true. I like to start at 25 yards and work my way up to 100 yards – and everything went predictably.

Overall, the Primary Arms SLx MD-25 with AutoLive is a speedster kind of red dot sight thanks to the ACSS reticle. With the AutoLive feature, those looking for a home defense or duty red dot will find value in it with my recommended battery replacements for every 6 to 12 months.

Features & Benefits

AutoLive Technology

AutoLive in action on MD25 RDS
AutoLive in action with illumination on (left) & in standby mode (right) - Image by Tina Fa'apoi (Own Work) for Target Tamers

With Sig Sauer’s MOTAC and Holosun’s Shake Awake as the most well-known motion sensor technologies in red dot sights, Primary Arms just upped their game. They added the AutoLive technology to the MD-25 Gen II model, and now it can compete seriously with similar red dots.

I tested the AutoLive and learned that it’s not adjustable (not that I’ve found), and I’d say the timer is set to about 2 minutes – it’s the most consistent time I tracked not unlike the MOTAC in the Sig Sauer Romeo 5 RDS. It’s sensitive enough that bumps and vibrations activate the illumination. Outside and mounted to a tripod, strong wind gusts kept the illumination on.

Considering its 12,000-hour battery runtime, I’d say Primary Arms made the smart move to give an ACSS red dot sight the AutoLive feature. It needs it.

ACSS-CQB Reticle

PA ACSS CQB reticle on MD25 rds
Image by Tina Fa'apoi (Own Work) for Target Tamers

The ACSS-CQB reticle was exclusively designed by both Primary Arms and Holosun to bring do-it-all benefits to a red dot sight. We’ve seen this reticle before in the Holosun HS503G that was exclusively made for Primary Arms, and now we see it again in the SLx MD-25 Gen II red dot sight.

The reticle has a fantastic blend of CQB and long-range elements in one. The horseshoe is 65 MOA in size with a chevron instead of a dot for the aiming point. To be clear, the tip of the chevron is your zero aiming point. The BDC dots are 1 MOA in size that gave me up to 600 yards of holdovers with my 5.56 loads.

I personally appreciate the horseshoe – it’s so fast to acquire and my eyes are drawn right to it. I never once had to ‘hunt’ for a dot. Using the chevron is a different experience to using a dot because the tip makes you feel like you can be more precise.

1x VS 3x with SLx MD25
1x (left) VS 3x (right) - Image by Tina Fa'apoi (Own Work) for Target Tamers

1 MOA dots are real good news because it means it will pair excellently with a magnifier. I tested this with my 3x magnifier. Though that 1 MOA dot is now a 3 MOA dot, subtension is still only 1 MOA. If you’re shooting long range, which is something the ACSS reticle is certainly capable of, this gives you the potential for absolute precision.

Now, the ACSS-CQB reticle offers a lot more than I would ever use. The included reticle manual provides nine BDC calibrated groups including a 12-gauge shotgun slug group. You can range center mass targets, vertically range targets, and estimate wind holds for 300 yards plus. In my opinion, the reticle is rather small for these ranging features without a magnifier if you actually want accurate reads.

Build Quality

Primary Arms SLx MD25 RDS
Image by Tina Fa'apoi (Own Work) for Target Tamers

Overall, the Primary Arms red dot sight is ruggedly built. The huge objective lens has a 25mm aperture that provides a wide FOV. It has an oversized look about it, but in reality, it’s barely longer and heavier than alternative enclosed micro red dot sights. It’s a solid optic with a solid build.

It’s both fog and waterproof rated at IP67 – as you can see, it’s also rated for dust. I tested it by drenching it in water. There are O-ring seals at the base of the turrets, so I left the caps on because in realistic conditions, I’ll have the caps on anyway – they only come off when sighting-in at the range.

Water testing the SLx MD25
Water-testing the SLx MD25 - Image by Tina Fa'apoi (Ow Work) for Target Tamers

I also accidentally drop tested it. I was walking outside with it in my hand, and it fell onto a concrete slab – so about 4 feet. Other than an itty-bitty scuff to the mount, it survived and has been fine since.

Some might not like the oversized illumination knob, but I do. It is a little weird for me to be using it from the left side, but I see the logic in putting it there – there’s no fighting for real estate space between using the windage cap or the knob.

Huge illumination knob on MD25
Large illumination knob - Image by Tina Fa'apoi (Own Work) for Target Tamers

In fact, one of my favorite features is this knob. It rotates both forwards and backwards past the “0” (off) position, and it can be rigged for intermittent off between the settings. It has just the right amount of resistance but is smooth to use – not too stiff. The one thing I don’t like about it is that the slot to tighten and loosen the battery cap is too shallow to effectively use with a flathead screwdriver. But you know what I figured out? The turret caps fit perfectly for this task!

SLx MD25 mounted to AR15
Image by Tina Fa'apoi (Own Work) for Target Tamers

Speaking of the turret caps, they’re oversized too. It makes getting them off and on easy. I like that they serve as the tool for adjustments. I do wish the actual ‘tool’ part was a little longer though. I kept slipping the cap up and down in the adjustment slot. Petty, I know, but thought I’d mention it.

It is a little bigger than other enclosed micro red dot sights maybe by half an inch and an ounce or two. But I think the added bulk and size are negligible considering its solid and rugged build. It looks like a durable red dot sight and feels like one too.

Mounting System

SLx MD25 riser mount and low profile mount
1.41" riser mount & 0.96" low-profile mount - Image by Tina Fa'apoi (Own Work) for Target Tamers

The PA SLx MD-25 Gen II red dot sight comes with a true multi-height mounting system. It comes with a low-profile mount, two spacers, hardware, and tools. The mounts are rugged, durable, and are stated to hold zero through heavy recoil and can handle significant torque.

With a pre-installed 1.41” height riser mount for an absolute co-witness and spacers for 1.54” and 1.64” heights, you can acquire the co-witness you want for use with irons or a fixed height magnifier.

I put the MD-25 red dot with the riser mount on my 10/22 for the sake of doing it, but my weld was too high. I put the low-profile mount on, and it’s perfect. I sent about 100 rounds downrange with this setup. The ACSS reticle makes for a rapid and fun experience, and with a 50 yard zero, you can go out to 175 yards with the last dot with .22LR rounds.

The tool for the mount is way nicer than the small Torx wrenches that we usually see with a red dot. Obviously, it’s a lot easier to use. The crossbolt heads are huge at what I’m sure is a T15 Torx size. The smaller wrench is for the mount screws.


PA SLx MD25 illumination
Max illumination against various surfaces - Image by Tina Fa'apoi (Own Work) for Target Tamers

I’m very happy with the illumination of the Primary Arms SLx MD-25 red dot. There are 11 settings with two of them dedicated to night vision compatible. During daytime use, setting 7-11 are visible. Settings 3-6 are best in low light applications and setting 1 and 2 were dimly visible at night.

I ran the illumination at 10 and 11 during the day at the range. I could sit comfortably at 8-9 in urban environments. Though I will state the illumination is daylight bright, it is not visible against reflective surfaces. However, I’ve yet to come across a red dot that is.

PA SLx MD25 with Gen 1 night vision
MD-25 with Gen 1 NV - Image by Tina Fa'apoi (Own Work) for Target Tamers

I did test the night vision settings with a Gen 1 monocular, and as you can see, the reticle is visible. Although you can’t tell from the image, it did not flare or wash out the FOV, though I think it could stand to be a tad dimmer for NV applications.

Excellent Pairing with a Magnifier

PA MD25 with Sig Sauer Juliet 3x magnifier
SLx MD25 paired with field-tested Sig Sauer Juliet 3 Micro magnifier - Image by Tina Fa'apoi (Own Work) for Target Tamers

In general, if the SLx MD-25 Gen II with AutoLive red dot sight is used inside 100 yards with a second zero distance, the ACSS reticle serves CQB purposes well unmagnified. Instead of a ring and dot, it’s a horseshoe and chevron reticle that is fast and easy to use.

The only catch is that to really make use of the subsequent dots for drop, it’s better done with a magnifier. While it does feel considerably small, it’s really not any smaller than a Holosun or EOTech EXPS3 reticle. The 65 MOA horseshoe is the same size as the 65 MOA speed ring in the Holosun circle dot reticle.

The dots in the SLx are 1 MOA in size and that is just like the 1 MOA dot in the EOTech reticles. This is ideal for use with red dot magnifiers for long range work, so I’d say beyond 200 yards.

Limitations of the Primary Arms SLx MD-25 Gen II

Battery Life

SLx MD25 RDS battery
Image by Tina Fa'apoi (Own Work) for Target Tamers

The MD-25 red dot sight comes with a CR2032 battery for immediate operation out of the box. There are a couple conflicting specs on battery life. The website states 10,001 – 25,000 hours of battery runtime while the box says up to 50,000 hours.

From what I’ve gathered, the 50,000-hour spec is for the MD-25 with the 2 MOA dot reticle only. The ACSS CQB reticle is rated for approximately 12,000 hours as stated elsewhere on the website and the manual. That’s not really great news considering that alternative red dots offer 20,000 hours plus these days – even those with a motion sensor feature too.

As is obvious, the ACSS reticle requires more power since there’s more to illuminate. The EOTech EXPS3 may have a somewhat similar reticle with a mere 1000-hour runtime, but it’s a holographic sight – so a different power consuming category all together. So far when it comes to battery life plus similar reticles, Holosun has the lead at 50,000 hours.

Overall, the battery life isn’t great, but it’s doable and is still considered long lasting. Its runtime equates to just over a year with medium illumination.

What about usage? Considering 'normal' usage is subjective, I’d recommend changing out the battery every 6 months or so if the MD-25 is sitting on a rifle in a truck with range use in between, and once a year if it’s on a home defense rifle.

Popular Questions About the Primary Arms SLx MD-25 Gen II

What does ACSS Mean?

In general, ACSS reticles are exclusive to Primary Arms. It stands for Advanced Combined Sighting System. There are variations of the ACSS reticle, and the SLx MD-25 Gen II with AutoLive red dot sight has the ACSS-CQB (Close Quarter Battle) reticle.
It was first seen in the Primary Arms and Holosun collaboration, the Holosun HS503B, that was exclusively made for Primary Arms. The ACSS reticle incorporates bullet drop compensation, auto-ranging, wind holds, and a center chevron.

ACSS-CQB reticle - Image by Tina Fa'apoi (Own Work) for Target TamersPA ACSS CQB reticle in the SLx MD25 RDS

What is the Battery Life of the Primary Arms MD-25?

The Primary Arms SLx MD-25 Microdot Gen II with AutoLive red dot sight has up to 12,000 hours of runtime from the CR2032 battery. The AutoLive feature helps to conserve battery power by automatically putting the illumination in stand-by mode after approximately two minutes.

Primary Arms SLx MD-25 G2 w/CR2032 battery - Image by Tina Fa'apoi (Own Work) for Target TamersPA SLx RDS CR2032 battery

What is the Difference Between the SLx MD-25 Red Dots?

The Primary Arms SLx MD-25 series varies by reticle. There is the 2 MOA dot model, the ACSS-CQB model, and this new Gen II model. The Gen II model has the ACSS-CQB reticle but is differentiated by the addition of the AutoLive motion sensor feature.

Does the Primary Arms Red Dot Sight Have Caps?

The SLx MD-25 red dot sight comes with the mounting system, spacers, hardware, battery, user manual, reticle manual, lens cloth, and the necessary tools. The Primary Arms red dot sight does not come with lens caps at all.

The eyepiece is on the larger side too, so rubber bikini caps from a different RDS will not fit right. I used my old flip-up caps from the Vortex Strikefire (Gen 1 archived model) and shimmied them on there. I’ll need to reinstall the eyepiece cap backwards so that the cap can latch.

Flip-up caps on the PA SLx MD-25 (left & top right) Snug magnifier bikini caps (bottom right) - Image by Tina Fa'apoi (Own Work) for Target Tamers
Lens caps on the SLx MD25

Does the SLx MD-25 Gen II Have a Lifetime Warranty?

The Primary Arms SLx MD-25 G2 is covered by the manufacturer Lifetime Warranty. Interestingly, comprehensive warranty coverage includes electronic failures which is something you do not see all the time. Also mentioned is normal wear and tear that can cause the red dot to malfunction – it’s covered.

Warranty on back of the manual - Image by Tina Fa'apoi (Own Work) for Target TamersPA RDS warranty

Primary Arms SLx MD-25 G2: Who Needs It?

Field testing the Primary Arms SLx MD25 red dot sight
Image by Tina Fa'apoi (Own Work) for Target Tamers

Overall, it can be asked who needs the Primary Arms SLx MD-25 Gen II red dot sight? The unique ACSS-CQB reticle complete with AutoLive and a robust, rugged mount and body makes it an excellent, all-round red dot for both CQB and long-range engagements. The better question is, who doesn’t?

Personally, I’ll be pairing this with a magnifier going forward as the reticle offers me long-range RDS potential with my AR-15. The MD-25 keeps me hitting the range, small game hunting, and I would put it on my home defense rifle, and that’s worth the money in my opinion.  

Tina field testing the PA SLx MD25

Thanks to Primary Arms for sending me this red dot sight to field test. Please note, even though this product was provided by the manufacturer, all my opinions expressed are my own and are not in any way influenced by any manufacturers.

Further Reading

Photo of author

Tina Fa'apoi - Expert Optics Tester

Tina is a renowned expert in optics, having written hundreds of articles for Target Tamers over the past eight years and owning an extensive collection of optic's including binoculars, rifle scopes, red dots, spotting scopes and rangefinders. With years of experience in creating instructional videos and field-testing various optics, Tina brings a wealth of practical and theoretical knowledge to the field.

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