Primary Arms SLx 5x MicroPrism Review

By Beyond Seclusion
Posted in #Gear
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Primary Arms SLx 5x MicroPrism Review

December 22nd, 2023

12:15 runtime

In today’s review, Beyond Seclusion gives the Primary Arms SLx 5x prism scope a full evaluation, including torture testing and range time. How does it fare? Check out the video and read the article to find out.

Are you familiar with the term “KISS”? I had not heard this until I was in the military, and it instantly became one of my top mottos in life. It stands for “Keep It Simple, Stupid”. When you take time to contemplate it, digest it and really embrace it, you see its applications for almost every aspect of your life.

primary arms slx 5x prism scope reviews
In this review, the author tests the Primary Arms SLx 5x prism scope (left). He also added a 1x optic on a 45˚ mount.

I believe it came about for instructions and training, and the idea was if you keep it simple, you have less room for issues and errors. I believe the “stupid” part came from if you are making it more complicated than it needs to be. The Primary Arms SLx 5x MicroPrism optic is about as KISS as it gets, as I will show you.

Why a Primary Arms Prism Scope?

I have found the KISS principle particularly helpful when reviewing and working with firearms and accessories. Personally, I found this to be exceptionally true when working with optics.

It became evident when working with electronic optics like night vision (NV) and thermal optics. Some of them are basically a computer on top of your gun, so I had to sit down with my reading glasses and pen and paper and study the owner’s manual just to figure out how to use the optic properly.

testing the primary arms slx 5x prism scope
During this testing, the author mounted the Primary Arms SLx 5x on a Springfield Armory SAINT. Visible is the FAB Defense GL-Core Impact recoil reduction stock he previously reviewed.

Like many of you, or even the majority of you, I just want to “plug and play.” Guns, for the most part, are pretty simple, but optics can get complicated. I have seen reticles that are so “busy” they are actually distracting, at least for me.

This is one of many reasons I wanted to review the Primary Arms SLx 5X MicroPrism scope. The prism optics are the epitome of KISS, and I think Primary Arms is setting the bar high. As you will see, they offer the ability to simply mount, point and shoot from 100-500 yards, but also include rangefinding and bullet drop compensators (BDC).

red dot reticle
In daylight conditions, the red dot is plainly visible. This image shows the 5x magnification at 500 yards.

Trijicon’s ACOG made prism optics legendary with their use in the military. They really set the standard for combat optics and showcased the KISS concept to the civilian market. They set the standard for KISS — tough and reliable optics.

Primary Arms is a company that has really capitalized on prism optics. They have really set themselves apart by making MicroPrisms. Typically, prism optics can be larger and heavier than traditional optics. Primary Arms’ MP’s are incredibly small and lightweight, and they have a huge selection of them for different calibers.

shooting with the primary arms slx 5x
A 5x power optic gives you significantly more reach than a 1x or 3x optic. That can mean an accurate shot at longer ranges or a more precise one closer in.

Until recently, their MP’s were pretty much 3X power. But not long ago, they released their SLx 5x MicroPrism Scope with a red illuminated ACSS Aurora 5.56/.308 reticle. Primary Arms MP optics are KISS, and they are also small, lightweight and streamlined as to not catch on things. And most of all, they are tough as nails. We will put this to the test with a Beyond Seclusion “Torture Test” just to make sure. 

[Don’t miss our Primary Arms SLx 3x MicroPrism review here.]

Testing the Prism Scope

My torture test starts with dropping from my second story balcony onto the deck below, or about 15’. Many optics fail here by the seal breaking, allowing the nitrogen — or whatever gas they used to make it fogproof — leaking out and allowing air into the optic.

water testing the shooting with the primary arms slx 5x
The author tested all of the claims made by the manufacturer, including water resistance.

That is why I follow this with the submersion test either into a bucket or my hot tub (105°) for 20-30 minutes depending on the optic’s IPX rating. If the seal is broken, water typically will leak in — but not always. The break may be small enough not to allow water in, but still let the gases out (or just not have enough moisture to be visible).

Thus, the final step is tossing it into the freezer for 30 minutes straight out of the hot tub. If there is any amount of air or moisture that leaks in, it will condensate on the inside of the lens. It will also further test the seals and waterproofing by expansion of water in places it should not be.

Many optics that cost twice as much as the SLx have failed this test. As you can see in the video, it passed with flying colors, kept zero when put right back on the gun in the same place, and still was able to hit the steel at 500 yards after the test.

I should mention Primary Arms has several lines of optics, from the most affordable “Classic” to the SLx, GLx, and PLx lines. They mostly differ in the quality of the glass or the expense of the glass. Make no mistake, the SLx is closer to entry-level, but the quality far surpasses the cost and the durability remains consistent throughout all the series as we witnessed.


The one feature I like most about the company’s MP’s like the SLx 5x is the BDC. The BDC allows us to determine the point of impact (POI) of our bullet at various distances such as 100-1,000 yards. The most common BDC’s cover 100-500 yards.

primary arms slx 5x bdc reticle
In this image, you can see the Primary Arms reticle in the author’s SLX 5x prism scope.

Most reticles these days that use a BDC will place dots vertically below the crosshairs that is zeroed to 100 yards. The dots appear below the crosshairs at distances that allow the POI to be reasonably accurate to hit an 18” target at those distances. To accomplish this the most effectively, the BDC needs to be specific to certain calibers with similar ballistics like the 5.56 and .308 or 7.62×39 and 300BLK.

[Be sure to read Ian Kenney’s article, How to Use a BDC Reticle.]

The SLx 5x I have is for the 5.56/.308 as they are very similar ballistically or POI at the same distances out to 500 yards. The owners’ manuals for different calibers will actually list the calibers that can be used with the BDC and even the best bullet weights and barrel lengths. For the most part, if you are using the correct caliber for the optic and the most common ammo used for it, you will hit the steel at those distances if you do your part. You may have to make minor adjustments when aiming with a slight “holdover” or under, but it works very well and is quick and easy.

shooting primary arms slx 5x 500 yards red dot
With a stable rest, the author used the SLx 5x optic on his Springfield Armory SAINT to hit targets at 500 yards.

To know the distance, the SLx 5x has included a range finder in the reticle. Not an electronic range finder, but simple line(s) that span a selected measurement at a particular distance. The vertical lines off to the side of the reticle cover a 5’10” object at various distances (100-500 yards). The same is easily integrated in the BDC horizontally, covering an 18” wide target at the same distances with the first line below the chevron. This allows you to quickly and accurately determine the distance with common measurements.

Illuminated reticles have also become very popular and greatly assist with shooting in lower light conditions, and this is the case with the SLx. It also makes aiming exceptionally fast when the crosshairs or chevron (my favorite) is lit up red.

The SLx comes with the ability to adjust the brightness of the illumination for the various lighting conditions. The only real problem with illuminated reticles is forgetting to turn them off so you don’t have a dead battery next time you go to shoot.

shooting primary arms slx 5x 200 yards red dot
The author engages a target at 200 yards without a rest using the Primary Arms SLx 5x prism scope.

Most companies these days have started using an auto on/off, meaning you can leave it on and when the gun does not move for a designated amount of time like 3-10 minutes (often you can adjust this), it shuts off but with the slightest movement, instantly comes back on.

The SLx has this function, and it is referred to as AutoLive. For folks like me who never remember to turn off the illumination, this is great as you don’t have dead batteries next time you go to shoot. The SLx shuts off after three minutes and instantly comes back on with the slightest touch or movement. For me, this is an absolute must with any illuminated reticle or red dot.


There is another saying, “Have your cake and eat it too”. The SLx 5x allows you to make quick and easy shots at 25 yards, but also all the way out to 500 yards as you can see in the video. It is affordable, simple to use, features quality glass, has an AutoLive illuminated reticle, is small and lightweight, and is tough as nails. What’s not to like?

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Springfield Armory® recommends you seek qualified and competent training from a certified instructor prior to handling any firearm and be sure to read your owner’s manual. These articles and videos are considered to be suggestions and not recommendations from Springfield Armory. The views and opinions expressed on this website are those of the authors and do not necessarily reflect the views and opinions of Springfield Armory.

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Beyond Seclusion

Beyond Seclusion

Drew of “Beyond “Seclusion” earned both his bachelor of science in nursing and his master of science in nursing from the University of Nebraska Medical Center. He has always had a love of the outdoors and shooting and has been shooting for 40+ years. He started a YouTube Channel reviewing guns and ammo just for fun and it is now a full-time business for him. He resides in southeast Nebraska with his lovely wife DeeDee and his two children Adree and Wyatt.

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