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.
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.
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.
Through the scope, seen above with illumination off, the reticle is clear and crisply defined.
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.
Same view, but with the illumination off. There are 11 brightness settings, including 2 night vision-compatible levels.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
Click Value: 1/2 MOA
Eye Relief: 2.67 inches
Exit Pupil: 0.4 inches
Field of View: 37.5 feet at 100 yards
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.