Prism scopes offer fixed magnification — typically between 1x and 5x — and compact size, like a red dot, but the use of an etched reticle means they function even if the electronics give up the ghost. Additionally, the reticles can be more complex and are adjustable for focus. Primary Arms is well-known for quality, yet affordable red dots and scopes, including a handful of prismatic scopes like the 2.5x example with ACSS reticle seen here.

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Form factor is compact for a scope, but long for a red dot. Of course, it’s smaller than a red dot plus magnifier, and in this case it’s zooming in on target with a fixed 2.5 times magnification. Length is 4.8 inches, height is 3.25 inches. It’s a dense little guy, though, weighing in at 15.66 ounces.

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Now, we’ve visited the ACSS reticle before. Most recently in the review of the Primary Arms 1-6x scope, which does a deeper dive on the use of the reticle than I’m going to do here. The bottom line is that this version of the ACSS reticle allows for very rapid, intuitive ranging and leading of human targets plus holdover marks out to 600 yards. These holds work surprisingly well for a whole slew of calibers, from carbine-fired 9mm to 5.56, .308, 7.62×39, 300 BLK, 5.45×39, 6.5 Creedmore, 6.8 SPC, and likely more.

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Through the scope, seen above with illumination off, the reticle is clear and crisply defined.

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Once again I’m impressed with the quality of the glass in Primary Arms’ optics. This is a sub-$200 scope, and the picture is clear and bright from edge to edge, with good color. It’s seen above with illumination on. It’s daylight bright. For CQB targets, the entire horseshoe acts as your red dot.

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Same view, but with the illumination off. There are 11 brightness settings, including 2 night vision-compatible levels.

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I don’t believe any prism scopes offer parallax adjustment, with most set to 100 yards. Whether this is technically the case with the PA 2.5x or not, it’s definitely parallax free within its entire intended range, from CQB range (let’s call it 15 yards) out to beyond 600 yards. If the animated GIF above is working for you then the end result of zero parallax is clear — the reticle says on target even if your eye isn’t properly centered. Those logs, by the way, are 25-30 yards away.

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One prism scope negative compared to a red dot is that there is a set eye relief distance. On a 2.5x like this, the exit pupil is large (0.4 inches) and, while the eye relief may technically be a very specific 2.67 inches, there’s some forgiving fudge factor built in. Acquiring a sight picture is fast and easy.

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The included Picatinny rail mount puts the PA 2.5x prism scope at standard AR-15 optics height. Don’t get too excited, though. Due to the magnification you can’t co-witness iron sights through it — the front will be far too blurred out to use. Also don’t get too excited about the included flip caps; they’re functional but cheap.

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While we’re on the topic of the mount, I may as well spill the beans here. The only negative I’ve experienced with this scope is that the two bolts holding the Picatinny mount to the integral base of the optic weren’t tight enough from the factory. They worked themselves loose on my first range outing a few months ago and the scope was wobbling around. A small drop of blue Loctite and judicious application of torque and this issue hasn’t reappeared.

Worth noting is that the mount is compatible with any full-size ACOG mount on the market. If this base with its two large hex nuts doesn’t do it for you, there are dozens of nifty QD ones available on the ACOG aftermarket.

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Turrets are capped, which some people don’t want in a tactical scope. However, with a BDC reticle like this, once the scope is zeroed the turrets really never get touched again, so I happen to be fully on board with caps. Adjustment clicks are 1/2 MOA and the clicks are easily audible, but not particularly tactile.

To the left of the elevation turret in the photo above — in front of it on the scope — is a mounting area. Primary Arms sells a little accessory Pic rail that fits here and can be used for a reflex sight. I don’t think I’d use it in this case, but on the 5x version of this scope (there are also a couple of 3x ones) having a no-zoom optic could still be handy. The other accessory available for this prism scope is a kill flash.

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The edge of a turret cap can be used for making adjustments, although with that generously sized, raised slot just about anything from the rim of a cartridge to a knife (yes, yes, I know they’re cutting instruments) to, yes, even a screwdriver would work just fine. Once broken in, even a fingernail can suffice.

On The Range

As much as I’d like to be, I’m not particularly talented at shooting with both eyes open. Red dot? Sure. Iron sights? Sometimes. But throw in some zoom and I throw in the towel. Color me surprised, then, at how easy two-eyes-open shooting proved to be with the PA 2.5x prism scope here. Maybe that’s just a sweet spot for accuracy-assisting magnification that stays this side of confusing my gray matter.

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Then again, it doesn’t hurt that diopter is adjustable from -2 to +2 so I could get the reticle nice and sharp despite my right eye needing a corrective lens at this point. The bright illumination and clear glass certainly played their parts, too.

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As always, using the ACSS reticle to range and hold over for range is as easy as pie (eating pie, not making pie). It’s impressive how accurate those holds are and how easy it is to adjust for different calibers. I’m more confident making hits on a target at 100+ yards with the 2.5x zoom than with a red dot. That probably seems obvious, but I wasn’t expecting to be so fast with this thing up close, too. No, not quite as fast within 35 to 50-ish yards as with a red dot, but I’m losing less time on that end than I’m picking up at longer ranges.

This prism scope was easy to mount — eye relief is more forgiving than with many scopes — and easy to zero. I encountered no functional issues with it whatsoever in a few hundred rounds of predominately CapArms .223 over the course of a few months, during which time this optic was bouncing around and getting buried by stuff in the back of my truck.

Conclusions

The “Primary Arms 2.5x Compact AR15 Scope with Patented CQB ACSS Reticle” has a hell of a long name, but it’s a solid, no-frills prism scope that doesn’t take up a lot of space or break the bank. Much more than just a magnified red dot, the ACSS reticle provides some heavy-duty functionality should you find yourself on a two-way shooting range.

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As there have already been a handful of torture tests published on these scopes, and because I like this scope and want to continue using it on my Tavor, I’m happy to take the other guys’ word for their extreme reliability. Of course it weighs almost a pound, so durable we much. Still, by all accounts they punch way out of their price class, and not just in durability but in glass clarity and overall functionality, too.

Specifications: Primary Arms 2.5x Prism Scope With ACSS Reticle

Primary Material: 6061 Aluminum
Length: 4.8 inches
Height: 3.25 inches with mount
Weight: 15.66 ounces with mount (as measured by me)
Illumination: 12 settings, red LED, CR2023 battery
Magnification: 2.5x
Click Value: 1/2 MOA
Eye Relief: 2.67 inches
Exit Pupil: 0.4 inches
Field of View: 37.5 feet at 100 yards
MSRP: $199.99

Ratings (out of five stars):

Glass Quality * * * * 
Pretty dang awesome in this price range. Clear from edge to edge, good light transmission, good color.

Reticle * * * * *
I kind of love the ACSS reticles.

Turrets * * * 
Standard in the budget price category. 1/2 MOA adjustments lacking well-defined clicks other than the sound. They do hold zero, though, so once set you’ll probably never revisit them thanks to the holdover reticle.

Overall Rating * * * * 
Clear glass, solid build, bright and crisp ACSS reticle, and enough magnification to improve accuracy while still allowing even me to shoot it with both eyes open. All at a very good price.

The .223 ammunition used in the making of this review was provided by CapArms. Their sponsorship of most of TTAG’s review-related ammo needs is a huge help, allowing us to review more guns and more gear more thoroughly.

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22 Responses to Gear Review: Primary Arms 2.5x ACSS Prism Scope

  1. I’m starting to wonder what the Primary Arms guys know that the rest of the optics manufacturers don’t. This may be my 3rd PA manufacures optic, and I have yet to spend as much money on them as I would on an ACOG. I wonder just what they did to get the price point so low.

    • “I’m starting to wonder what the Primary Arms guys know that the rest of the optics manufacturers don’t.”

      I suspect Primary put in the leg work to find a China manufacturer that offered the best quality to price point.

      That old Russian saying of not letting the best be the enemy of the good enough…

    • I am going to offer a counter point. I have had 3 PA scopes now, a 4-14 mil dot that is still on my 308 AR, the 2.5x reviewed here, and the 1-6 acss reviewed earlier. I had to return my first 4-14 after a few months cause it broke after relatively light range use. I just sent back my 1-6 today cause of the same problem. So far the replacement 4-14 and the 2.5x are holding up, but I have not put very many rounds on them. I am probably going to replace the 1-6 with their acss red dot + a magnifier. I still don’t think they are a bad company but I have had less than perfect results with their scopes. The first time I counted it as a fluke, but now that it’s happened twice I am getting more wary of their products. Just a warning.

      • One thing to be aware of is that they’re very responsive when it comes to problems with their products. It’s basically what you’re buying, compared to just getting that same glass directly from China (which you could if you really wanted) – customer service, aka insurance in case you get a lemon.

  2. It’s a great scope for the price (as is their newer 3x model). For someone wanting to upgrade from iron sights, but so torn between the various choices – red dots, 1x scopes, full size scopes etc – that they’re unable to choose, this is a decent (and CHEAP) compromise option that will work “good enough” for most everything.

  3. I’m done with the bottom ads on this site.
    There are better ways to keep a site free. Disappointin, but every decision has a consequence. Enjoyed the articles.

    • If using Firefox or Chrome browser, use the ad-block add-in. Makes life so much easier. I can’t even look at this site from my mobile device. The ads are awful!

  4. In your animated GIF, I see the point of aim moving around quite a bit with camera position. It’s possible the rifle wasn’t steady when you were filming that, but it doesn’t look “parallax free” at that range from that series of images. Either way, nothing is going to be parallax free over that long of a range. It’s not optically possible. That’s something that needs to die in optics reporting. I’d like to find out who started that and clock ’em. When you move your head relative to the scope, everything appears to move. Stuff up close appears to move much more than stuff far away. If the optic aims true with adjusted parallax at pretty much point blank, that means that the reticle also must appear to move a bunch when you move your head which would make it aim very very not true at even moderate distances with your eye off center. In other words, you don’t really want it set for point blank. To go back to your GIF, look at how much your reticle appears to be moving (not much, really) and compare that to how much the terrain on the edge of the field of view appears to be moving (a good bit more). Unless those are exactly the same, you’ll have parallax. There is some range at which that relative movement of the reticle is exactly the same as the apparent movement of the target when you move your head. At that range and only that range is the optic “parallax free” (though you can adjust what range that is on some optics). I’m not just trying to be pedantic here. We should all strive to be precise when talking about (anything, really) firearms and their accouterments.

    • I’m not seeing what you’re seeing in the GIF. As far as I can tell, if I were aiming at a bottle cap with perfect, centered eye alignment the reticle would stay on the bottle cap no matter where that image is in the eye box. I just don’t see it moving in that little animation. It doesn’t in real life, either, as long as the target is around 15 or more yards away, and inside of that the parallax error is minor enough that you’d stay in the A zone regardless and it’s hard to notice unless you’re specifically looking for it. You are correct in that “Point blank to 600″ was probably too generous, so I’ve made an edit to be more specific and accurate there and a little less hyperbolic. Thanks.

      To be a totally candid and argumentative jackass, though, as I’m wont to do haha, if parallax error is so small as to be well within the accuracy ability of me and/or my rifle anyway (e.g. there’s 1/8” of parallax error at 100 yards from one side of the eye box to the other) or simply undetectable with the human eye, going into a dissertation in a review explaining how there technically is parallax from a scientific/engineering perspective, even though you won’t be able to notice it, does actually seem pedantic. I have to be more concerned with the practical aspect of using something and try to stay out of the weeds. I already feel the review is a bit longer than it should be as-is haha

      • I don’t know where that thing is set, so I can’t comment on how much relative movement you’d actually expect to see, but in my defense I’d counter that there is a reason that parallax corrections are available on a huge range of scopes, usually from ~50yd out to infinity. If you had parallax free at fifteen yards, the difference in point of aim if you were off center would be far from academic at 500.

        • Magnification level certainly has a lot to do with it. With a 1x, no magnification optic we see vastly larger “parallax free” ranges than with something that zooms in quite a bit, which is a big reason why parallax will be fixed on many/most low-zoom optics (even from very high-end, expensive brands like on the US Optics SR-6 sitting next to me) but is almost always user-adjustable on higher-zoom optics regardless of price range…it just has to be. Some of that is due to the focus of the reticle actually getting off, though, too…

  5. I’ve been considering this for my beater RRA. Always seem to get put off a bit by the weight, eye relief, eye box and battery life of Prismatics (vs RDS). But having a mild astigmatism makes these wonderfully enjoyable for shooting at the range, so it remains on my short list.

    • I own one of these on a tavor and I can tell you it doesn’t feel heavy. In fact it doesn’t feel any heavier than a basic red dot.

  6. “…it’s definitely parallax free within its entire intended range…”

    No, it’s not. Simply put: that’s not possible.

    There are a lot of ways to reduce parallax but it cannot be eliminated.

    The most common method to do this is to focus the sight to infinity thereby reducing the parallax to something you barely notice unless you get into some odd positions and have a target that’s not at the focal distance of the optic. Significant testing with a skilled shooter will still detect parallax in this case though. “Parallax free”, like a “free lunch”, doesn’t actually exist. You might not be able to detect it without some serious work but the parallax phenomenon is there.

    • You are correct. No argument on the technical basis of what you’re saying. Please just realize that “parallax free” is an accepted industry term for “not noticeable” and in the case of this optic, from ~15 yards and beyond, there really is no visible parallax and there is definitely no meaningful parallax. I DO have a couple red dots here that are bad enough that they’d throw you off target if your eye isn’t exactly in the right spot and that were really freaking hard to zero at 25 yards because of it. This PA unit is as close to zero parallax as exists without being able to adjust for it, and beyond a certain minimum distance it simply is not detectable.

  7. I bought the slightly more expensive Vortex Spitfire – also an etched reticle. As someone with rather bad astigmatism, the etched reticle is much, much nicer than a holographic, which is useless to me and still a lot better than a red dot, which isn’t as bad as a holographic but can still be frustrating.

  8. After some bad PA experiences some years years ago, I won’t go near the stuff. Or any other chicom junk. Buy once, cry once.

    • The thing about Primary Arms is you could buy 2 or 3 times and still pay less than what you’d get with a trijicon or similar scope, and that’s before you factor in their excellent return/replacement policy. I have never been burned on a PA scope even though I’ve had 2 go bad on me.

  9. I recently added a PA 5x ACSS on a POF 556 and love it. No issues, clear and holds zero after >1,000 rounds. Couldn’t bring myself to spend near the cost of the rifle on an ACOG.

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