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Primary Arms SLX 3-18x50mm FFP Review [Updated 2023]

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Primary Arms prides itself on producing affordable optics and gun accessories that can still measure up well with the best in the market. Apart from their affordability, primary arms products are durable and long-lasting. One primary arms scope that has surprisingly managed to stay under the radar is the primary arms SLX 3-18×50 FFP scope.

This is a first focal plane scope that allows the reticle to remain the same at every magnification level. With such a wide magnification range and a matching objective lens size, you’ll experience quality images from this scope. The scope is most suitable for a .308 win., chambered weapons, and 5.56 NATO precision platforms.

The underrated SLX 3-18×50 primary arms scope can easily become your go-to option if you realize its full potential. While not many review sites online look towards this scope, we’ve seen what it can do and will be going on a deep dive into its features in this piece. You’ll see everything about this scope so you can decide whether to buy it or learn how to effectively use it if you already own the scope.

Features of Primary Arms SLX 3-18x50mm FFP Scope

Features of Primary Arms SLX 3-18x50mm FFP Scope
Image Source: https://www.primaryarms.com

What are the main parts and characteristics of a scope? Before you answer that, you should know these are the things standing out in the scope, the factors that most scopes are judged by, and the mechanisms they use that make them different.

1. Magnification

If you want to cover a wide range of distance with your scope, a scope like this primary arms SLX should be on your mind. It sports a minimum magnification of 3x through to a maximum level of 18x. This covers short distances through to long distances up to 1000 yards. You can use the scope for shooting across various distances.

Scopes like the Primary Arms SLX with a wide magnification range allow shooters to hit targets across varying distances without having to use a new scope. Hunters and tactical shooters alike will find a scope like this quite valuable as they can stay far away from their targets to keep the anonymity and still get accuracy.

Bonus Read: The 5 Best Rifle Scope for Deer Hunting in 2023

2. Objective Lens

Objective Lens
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For a scope with a maximum magnification of 18x to produce clear images at magnification levels closer to the maximum, an accompanying wide objective lens, among other things, is required. Objective lens size is the size of the outer lens closest to the target.

This Primary arms SLX scope has an objective lens size of 50 mm. This is huge even for a scope with a maximum magnification of 18x. Primary Arms wants to achieve a great level of clarity with this scope, and that is why it has installed such a wide lens size. This lens is responsible for light intake into the tube. The light entering helps to brighten images formed inside.

Generally, higher magnifications require more light to get clear images. Without the right amount of light at these levels, the images formed will be blurry and poor.

3. Reticle

This is a first focal plane reticle where the reticle changes in size as you move the magnification; this makes it true at every power level. It is fitted with the special patented primary arms ACSS HUD DMR reticle. This reticle is one of the best reticles for moving target shooting. It is an illuminated reticle with red color available. However, it does not come with night vision, so it can be used in low light conditions but not in complete darkness.

The reticle is perfect for hunting and tactical shooting involving moving targets, like military operations. This reticle comes with so many features like bullet drop compensation to estimate the flight of the bullet, range estimation, moving target leads, and windage holds. The three hold-over points in this reticle account for the different speeds of the moving target and enable better accuracy.

First focal plane reticles with their changing reticle size and the multiple holds over for improved accuracy enable the shooters to quickly acquire their target. It is easy to make these quick target acquisitions because you do not need to do any calculations or physically dial when aiming.

4. Turrets

Image Source: https://carolinafirearmsforum.com

There are three turrets on the primary arms SLX 3-18x50mm scope. These turrets are the elevation, windage, and parallel adjustment dial, which also serves as the reticle illumination dial. The turrets use a mil rad adjustment type with 0.1 mil rad per click value.

Windage and elevation adjust the distance of the intended target and actual point of contact, while the parallel knob is used to bring the reticle and the target to the same plane to remove blurriness.

There’s also a quick-adjust diopter and power ring on the body to improve the scope’s focus and move magnification levels. The windage and elevation turrets have a push-pull locking mechanism that prevents accidental shifting of your zero.

The illumination turret that doubles as the parallax turret have 6 available brightness settings for daytime shooting. It also includes an off switch between each setting so you can make quick changes.

5. Build And Durability

For an affordable scope, this primary arms SLX 3-18x50mm scope is built impressively with durable materials and a sleek body. However, its large objective lens size and protruding turrets make it somewhat bulky and large.

The scope is 13.2 inches long and weighs 25.4 ounces which is slightly heavy. This is no surprise since it sports a large objective lens size, among other things. The tube is 30mm wide, while the scope is made from durable 6061 aluminum material. The material ensures the scope is shockproof and can withstand recoil pressure from the rifle as well as small bumps.

It is sealed tightly to make it waterproof with an IP67 rating and nitrogen-purged to keep it fogproof so you can use it in wet conditions without fear of damage. Its matte finish reduces glare and keeps your position hidden. The removable fin on the power ring ensures quick magnification adjustments by moving the fin to the desired position.

6. Glass And Optical Quality

Glass and Optical Quality
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It uses high-quality glass that many claims to be as clear as the vortex viper, which is not in its price bracket. The lenses are fully multi-coated to ensure better light transmission, which produces better images.

The optical capability of a scope depends on the type of glass and coatings available. The coatings feature an anti-reflection layer that prevents the reflection of light from the glass surface.

Also Read: How to Look Through a Scope – The Right Way

7. Eye Relief And Field of View

Eye Relief and Field of view
Image Source: https://www.primaryarms.com

When looking through the scope at 100 yards, the maximum field of view you can see at the lowest magnification is 36.7 ft, while the maximum you can see at the highest magnification is 6.2 ft. These distances allow you to see the surroundings of your target for better awareness. The adjustable parallax can be set from 10 yards up to infinity.

The eye relief of the primary arms SLX 3-28×50 is 3.9 inches at the lowest magnification and 3.5 at the highest magnification. This is long enough to avoid injuries from the recoil of the gun. You can also take up a few odd angles and still see through the scope.

8. Price

The SLX scope is a mid-range primary arms scope that sits above the low-budget variants but below the premium models. This puts its price in a decent range. Not the most affordable in the market but also not completely out of reach for many people.

9. Accessories and Warranty

The primary arms SLX 3-28x50mm scope comes with several accessories that make your life easier and saves you money. It comes with one CR2032 battery to power the illuminated reticle. There are also lens covers to protect it from dust and scratches when not in use.

The scope is covered by Primary arms lifetime warranty that covers the manufacturer’s defects, workmanship errors, and even wear and tear. The warranty can also be passed down to another person and does not need a receipt to activate. Primary Arms backs this scope well.

Also Read About: Vortex Copperhead 4-12×44 Review {Latest 2023 Review}

Pros and Cons of the Primary Arms SLX 3-18x50mm FFP Scope

Here are reasons for and against buying this scope for your moving target shooting:


  • Wide magnification range of 3-18x covering an impressive range
  • Wide objective lens diameter of 50mm to ensure light enters and images are clear even at higher magnification
  • Quick target acquisition
  • 6 daylight brightness settings
  • Impressive primary arms lifetime warranty
  • Good eye relief of 3.9-3.5 inches
  • Patented ACSS HUD DMR reticle
  • Shockproof, waterproof, and fogproof body


  • Not compatible with night vision
  • Bulky due to the wide objective lens size


Severely underrated, this primary arms SLX 3-18x50mm scope can become your go-to option if you’re shooting moving targets with its specialized ACSS HUD DMR reticle, which is one of the best for shooting moving targets. Its decent price point and impressive warranty, among its other features, make this an even more attractive option.

About Author

James Towndrow, a NRA-certified Firearms Instructor. During a career of 18 years had won several shooting competition including major leagues. Taking all those experience down the road, is now a successful Shooting Instructor in Texas, US.