Chad Wallace

February 28, 2026

Optics, Review

Primary Arms SLx 4.5-27x56

Chad Wallace

February 28, 2026

Optics, Review

Primary Arms

SLx 4.5-27x56 FFP Review

Inexpensive, high quality long range optics are starting to become more prevalent in today's market. Primary Arms Optics recently released their SLx 4.5-27x56 first focal plane scope. This thing is a beast, in a good way. It is available with two different ACSS reticles: the Athena BPR MIL Reticle and the Deka G2 Reticle. I received the Deka reticle, which was the one I would have chosen anyways.

The SLx line of optics from Primary Arms is what I call their “value” line. What that means for the customer is that you get a ton of features for a reasonable price. For instance on this SLx 4.5-27x56 you get an illuminated first focal plane reticle, 34mm tube, finger adjustable turrets, fast focus eye piece, a throw lever, and a zero stop. This line also has some good glass. Because the 4.5-27 is in the SLx line, you do get a scope that might weigh a little more than Primary Arms’ GLx or PLx line, but I expect that in a value line product.

Primary Arms Optics SLX 4.5-27x56 is loaded with options. I mentioned a few before, but let us get into them more. The 34 mm tube and 56 mm objective lens help to allow more light through the lenses. At lower power, this is not really a problem, but as the magnification increases, light going through the scope to your eye can diminish. So you get a brighter picture than say a 30mm scope with a 50mm objective lens. Another advantage of the 34mm tube is that it allows more elevation and windage adjustments. In the SLx’s case, it allows for 32 MIL’s of adjustment at 100 meters, or about 115 inches.

The ACSS DEKA G2 reticle is nice. The Deka is a MIL reticle that has a bunch of features, including ranging. First, it is a crosshair style reticle, no “Christmas tree” style here. I really like this style of reticle because it doesn’t clutter up the viewing space, allowing one to see their target more clearly. The inner part of the reticle has tiny marks every 0.1 MIL. Slightly larger ones at 0.5 MIL’s, and bracketed “T” marks every MIL. Then every 2 MIL mark has a number out to 10 MIL’s. So 2,4,6,8, and 10 are marked with those numbers. This applies to both windage and elevation. This marked portion of the reticle is the illuminated section, including the center 0.1 MIL aiming dot. The center dot gives you a really accurate aiming point. If you want to only see the illuminated part of the reticle, you are limited to about 15x magnification. At the full 27x, you see about 14 MIL’s of the reticle, 7 on each side of the aiming dot. After the 10 MIL mark, you get a solid line with 20, 30, and 40 MIL marks. This outer portion is not illuminated. The top portion of the reticle has some ranging lines, which are also illuminated. These are used to determine the approximate range of a 5 foot 7 inch tall, and/or a 19 inch wide target. The ranging marks start at 300 meters and go out to 1000 meters. I have one minor complaint about the reticle, I would like the stadia line, that has the marks on it, to be smaller than 0.1 MIL. Maybe something like 0.05 MILs. Mainly because this line just holds the markings, which are 0.1 MIL wide. Other than that, I really do like the configuration of the ACSS DEKA reticle.

Since the reticle just was explained, now maybe we should adjust it to our rifle. The turrets on the SLx 4.5-27 are fairly large and nicely textured. This makes them easy to adjust with or without gloves. The clicks are quite good for being in the SLx line. They are positive with very little “mush” to them. These turrets also adjust the optic in 0.1 MIL increments. The windage turret is capped, but it can be set to a zero after sighting in the rifle. This windage turret also has right and left markings on it. So once you set the zero, if you need the bullet to go left 1 MIL’s, you just turn it to “1L”, or “1R” if needing to move the impact to the right. The elevation turret is one place the SLx really shines. It is a large target style with an adjustable zero stop. Having that zero stop makes it super easy to adjust the optic back to its base zero. One revolution on the elevation knob is also 10 MIL’s of adjustment, making range adjustments easier to calculate. If you don’t like the target style elevation turret, Primary Arms also supplies a standard height turret. Both of these turrets have markings on them, neither one is capped. On the left side of the optic are the parallax and brightness knobs. Both have decent texturing. The parallax knob turns easily, even if it is harder to get clear at longer ranges. The brightness knob turns harder, but has positive detents for the 6 brightness settings. It also has “off” positions in between each numbered “on” position. Brightness is really good, but it is not daylight bright illumination. Unless it was a really dark day, I didn’t really use the illumination.

I was impressed with the SLx 4.5-27’s clarity. At lower power levels, up to about 20x, it is super clear and bright. Okay, it is pretty bright all through the magnification range. When you get up to about 25x, the clarity seems to drop a tiny bit. It is still usable at 27x, you just notice it. I was still able to see, and hit targets at 1000 yards without any problems. Okay, seeing them yes, hitting them was more of a challenge. But that was not the optics fault. Part of the reason the clarity drops off at long range is due to the touchy parallax adjustment. It adjusts fine at 100-500 yards, but as the magnification and range increases, it is harder to adjust to get a clear picture. It can be adjusted for a clear picture, it just takes very small movements. Don’t let these complaints scare you off, the SLx 4.5-27 is still a very capable optic out to 1000 yards and beyond.

Stump is approximately 1100 yards, Optic is at maximum power (27x)

I ended up mounting the SLx 4.5-27x56 on my Bergara .308, which sits in an MDT chassis. The rifle already has a 20 MOA rail to mount an optic on. This gives me extra adjustment to use. Because of this, with the SLx 4.5-27, I get a full 20 MILs of “up” elevation adjustment. This lets me dial out to a range of about 1400 yards, which is about 200 more than I will ever shoot this rifle. I shot this optic out to 1100 yards. That is how I know that the parallax adjustment gets really touchy. It takes a bit to get a clear picture at that range, but it is doable. The turret adjustments are nice and make it easy to adjust to whatever range you are shooting at. The SLx 4.5-27 would make a great entry level PRS or long range scope. It did everything I needed it to and more.

If you are looking for that affordable, quality, long range optic, the Primary Arms SLx-4.5-27x56 would be a good choice. It has decent clarity and exceptional brightness. Once it is adjusted, it can easily see targets at 1000 yards and beyond. It also has 2 different reticle options, a Christmas tree style and the DEKA reviewed here, so you can get the style you want. If you are looking at getting into long range shooting, or just need a good high power magnified optic, go check out the SLx 4.5-27x56.

Firearms Insider Reviews - Key Points

Claim to Fame:

Quality long range optic at value price

Target Market:

Those wanting a long range, clear optic that doesn’t beat you up on price. Also entry level long range shooters

Features, Benefits, and Specifications of this product:

Battery Type: CR2032 3V Lithium Coin
Click Value: 0.1 Mil
Focal Plane: First Focal Plane
Illuminated: Partial Red Illumination
Magnification: 4.5X - 27X
Mount Compatibility: 34mm
Reticle: ACSS DEKA G2 Mil
Total Elevation Adjustment: 32 MIL
Turret Features: Tactical / Target Profile, Finger Adjustable
Lifetime Warranty
Reticle stop
Field Of View @ 100yds: Low: 26.69 ft. / High: 4.46 ft.
Length: 13.78 in
Eye Relief: 4 in
Weight: 32.6 oz.

What other aesthetic options or finishes are available?

Athena BPR Mil Reticle

What others are saying?:

5 out 5 star from Texan at OpticsPlanet.com

Scope is super clear. A great value for the money. My second scope of this line.

Link to other reviews:

Nothing found as of publishing

Price point:

MSRP = $549.99

Retail = Same

I need it now! Availability:

Primary Arms, Optics Planet, or your local gun store

Our Rating:

Pros:

Reticle choice
Clear and bright glass
Target turrets
Illuminated reticle
Zero stop
Price

Cons:

Parallax adjustment is touchy
Heavy

Score: 8.00 Great

Favorite Link: Primary Arms GLx MD-21 Review

Chad Wallace

May 3, 2025

Review, Optics, Gear

ZeroTech Thrive HD 1-8x24

Chad Wallace

May 3, 2025

Review, Optics, Gear

ZeroTech Thrive HD

1-8x24 Review

ZeroTech Optics sent Rusty and I one of their new Thrive HD 1-8x24 Low Power Variable Optics (LPVO). For a bit I was trying to decide what to put it on. Then SRU and Foxtrot Mike made the decision for me, by sending me a bullpup kit. The new Thrive HD was a perfect fit. ZeroTech’s new LPVO has some great features, some clear glass, and some other stuff.

The ZeroTech Thrive HD 1-8 is the first LPVO in the Thrive lineup. The Thrive series of optics is primarily built for hunters, but that does not mean that there is not crossover into other types of shooting. In fact, the bullpup kit I mounted it on probably won’t see a day of hunting in its lifetime. Unless the random coyote pops up when I have it on hand. Being that the Thrive HD 1-8 is a second focal plane optic, it does lend itself nicely to hunting. However, the way the reticle is set up also works well for run and gun type competition. I think it is more of a dual duty style of optic.

Construction on the Thrive HD is somewhat simplistic. ZeroTech constructs the 1-8 using 7075 T6 aluminum. 7075 is stronger and lighter than the typical 6061 that a lot of other scope manufacturers use in their $450 price range LPVO’s. It weighs in at 22 ounces, which also falls right in line compared to other LPVO’s. As with most LPVO’s, the Thrive HD uses a 30 mm outer tube diameter. The adjustment turrets are of the capped style. This gives it a clean look. Since this is not a scope for long range work, the capped turrets do not detract from anything.

ZeroTech throws a few “extras” in the box that are pretty nice. Up first is the Thrive HD’s flip up covers. These are not your everyday plastic ones. They are aluminum and screw on. Using the supplied tool, you can tighten them down to your preferred location. This is especially nice for the ocular lens with the fast focus eyepiece. Since you need to focus the eyepiece to your eye, you can then loosen the flip cap, align it, and re-tighten it, so it works correctly. The 1-8 also comes with a removable throw lever. This throw lever uses a little rail type attachment. So one just slides it on and tightens the little screw. Also included is a neoprene style one piece scope cover. It is a really nice cover.

When looking at optics, the reticle can be really important. The Thrive HD 1-8 uses ZeroTech’s PHR 4 illuminated reticle. This reticle, for some reason, reminds me of the old German #1 reticle. It is not even close, but here is my best explanation. The PHR 4 has 3 fairly thick crosshairs, 1 up from the bottom and then 1 on each side. These then reduce down to 0.5 MOA thick lines. These lines extend 7.5 MOA out toward the center reticle. There is then a 2.5 MOA space until the center reticle starts. Yes, there is a center reticle. The center reticle is also the part that illuminates. They call this a floating reticle and is more akin to a standard small thin crosshair reticle. It measures 5 MOA. It also has a 0.5 MOA dot in the center. Of course all of these measurements are at 8x. There are 5 brightness settings on the Thrive HD. On/Off and adjustment are a little different than what you might be used to. On the left side of the scope is the battery cap. In the center of the cap is a button. This button is pressed to turn on the red illumination, in the last setting that was used. Just push it again to cycle through the 5 brightness levels. It cycles from brightest to darkest, and then repeats itself. Since the Thrive HD does not have any shake awake function, you will want to remember to turn it off when done. To do this you just hold the button down for about 3 seconds and the illumination turns off. The brightness is not daylight bright, but is very useful. ZeroTech does not sell the Thrive HD as daylight bright, so I was not expecting it to be.

The Thrive HD 1-8 has capped turrets for adjustment. To adjust the LPVO, you must first remove the caps. Underneath are some decently nice knobs. These are easily adjusted with your fingers. The ¼ MOA clicks are a tiny bit mushy, but can be heard and felt easily enough. The ¼ MOA adjustments are a nice feature. A lot of 1-8 LPVO’s have ½ MOA adjustments. These windage and elevation knobs can also be set to zero, after the initial sighting in. That way you at least have a reference when making further adjustments.

I was impressed with the clarity on the Thrive HD. Looking through it produces clear images with no detectable color differences. It did not seem to matter if it was at 1x or 8x, nothing seemed distorted. However, the eyebox on the 1-8 is unforgiving at 8x. You have to be in just the correct spot to get a good image. At 1x, I did not notice any problems getting a clear picture through the eyebox. This is my only real complaint about the Thrive HD 1-8.

As mentioned, I mounted up the Thrive HD to a bullpup. This required me to put it in a higher optics mount. I used a Geissele 1.93 scope mount and it was perfect for the 1-8. You can read the SRU review to find out why the mount is turned around. I mention this so you get the idea of how I used the Thrive HD. This LPVO is really clear for its price range. I would compare it to some optics that are priced a couple of hundred more. It really shines at 1x with the PHR 4 reticle. Then the 8x gives you enough magnification to identify targets easily. The adjustment ring, with its optional throw lever, operates super smooth. Those flip covers take a little bit of getting used to, they are a bit stiffer than the normal ones I use. All those little add-ins are a nice touch too. The Thrive HD did everything I wanted it to do.

The Thrive HD 1-8x24 is a good option for those looking for a LPVO. It is decently priced for the quality and clarity you get. It has a very useful illuminated reticle. The throw lever, to adjust the magnification, is super smooth. You really get a lot of optic for your money with the ZeroTech Thrive HD line. Go check out Zerotech’s line of optics, they might have something that fits with your shooting style.