Primary Arms GLx 4-16x50mm FFP – Review

The biggest endorsement there is for a scope is that it works. I’ve been testing the new Primary Arms GLx 4-16x50mm FFP Illuminated Mil-Dot scope and it works! It’s got some great features that are better executed than scopes costing twice as much money.

I mounted the GLx on a Franken 6.5 Grendel AR-15 and sighted it in. It shot the following group with factory Hornady 123 gr American Gunner ammo. 

This group was shot prone from a bipod.

I then took it with me to the family ranch in Nevada where, after dialing in elevation and windage, my 5-year-old nephew hit a 15-inch steel plate three times in a row at 500 yards in a steady 20 mph wind. 

Since then I’ve had it out to 1000 yards. The turrets have tracked consistently and the scope has just worked. 


I actually spent some time on the phone with a Primary Arms optical engineer and learned some interesting things about the PA GLx 4-16×50.

The scope was designed and engineered in the USA. It’s made in the Philippines.

The turret/tracking system has been upgraded to be steel on steel versus brass on brass which adds to the longevity of the tracking.

Primary Arms has tested the scope with thousands of revolutions on the turrets and measured less than 1% error.

They have also recoil tested the scopes with thousands of actual rounds, not computer simulated recoil. Scar 17’s are famous for destroying expensive military scopes due to the way in which they recoil. The PA GLx was tested with thousands of rounds through a Scar 17 without failure.

Zero Stop and Locking Turrets

The turrets have both an easily re-settable zero stop and a locking feature that requires a simple push of a button to free the turret for rotation.

I thought that resetting the zero stop was quite simple. Dial the optic in. Loosen the set screws and put the turret back to zero. Retighten the set screws.

To turn the turret simply push the triangle-shaped button on the front and the turret unlocks.

The turrets have aggressive knurling and when you turn the turret you can both hear and feel the click. The detents are very positive and it’s not difficult to count by feel. The numbers and lines on the turret match up with the line on the scope for dialing quickly.

The scope I tested was in mils and the turrets dialed in 1/10 mil increments. From the locked position the turret will turn down 4/10ths below the zero stop. Each revolution of the turret is 10 mils or 36 MOA which is enough to get even the slowest cartridges well beyond 1000 yards. My scope dialed 10.6 mils from zero. If you add the 4/10ths below zero there is a total of 11 mils of up travel. Total Elevation and Windage adjustment is 25 mils.

The windage turret works the same as the elevation turret except that each number either has an “R” or an “L” next to it so that you know that you are dialed for Right or Left windage. It’s a well thought out and well executed turret system.

The scope both tracked accurately and returned to zero each time.

Side Focus, Illumination, and Reticle

The side focus knob has markings at 25 yards, 50 yards, 100 yards, and then goes in 100-yard increments to 1000 yards. It ends at the infinity mark. The side focus will actually turn in closer than the 25-yard mark which is fantastic for rim-fire shooting.

The Illumination knob has 10 settings with an “off” in between each setting. The illumination is bright but not daylight bright as it is sometimes described in lower power scopes. Still, in lower light situations and on lower power the illumination is helpful especially since this scope features a First Focal Plane reticle which gets bigger and smaller with the power.

Actual image of the illumination through the Primary Arms GLx 4-16x50mm FFP.

The major advantage of an FFP reticle is that the wind and elevation holdovers are accurate at any power, whereas on SFP reticles the holds are only accurate on a designated power, usually the highest magnification.

This particular scope I tested used a mil-dot reticle. There are other reticles available in this scope but this particular reticle is an Army Mil Dot reticle which means that the distance between dot centers is 3.6 MOA.

I liked the floating center dot.

Eyepiece, Maintube, & Magnification Ring

The eyepiece features a quick-adjust diopter that worked exactly as it should for making the reticle focus to each unique eye. The eye relief is a substantial 3.6 inches. The field of view is slightly above average as compared to several other popular optics.

The maintube is a one-piece, 30mm, 6061-T6 aluminum tube. The entire scope only weighs 23.5 oz and is just 13.8 inches long.

The magnification adjustment is aggressively knurled but attractive and not painful to the user’s hands. It moves smoothly to adjust from 4-16 magnification. It features a “fin”, or throw lever, that can be moved to two other positions or be removed altogether.

The “Fin”


Primary Arms claims that the GLx scope has “Premium Grade Glass” that they describe as “Fantastically clear, low dispersion glass…”

I thought the optics were good. My socks weren’t blown off. I’m not going to tell you that I thought it was better than a $2800 Nightforce or $2200 Leupold. I do think it’s pretty darn good when you consider that the scope only costs $699. I could see sufficiently at 100 yards and I could see sufficiently at 1000.

Below is a video of me shooting at 600 and 700 yards. The view is through the scope. The optics are better than what the video shows and you can clearly see that the optics are excellent, good, sufficient, likely better than most other scopes in that price point, no doubt.

With the 50mm objective lens the glass gathers plenty of light for most shooting situations.

Watch the video for a view through the scope.

Don’t judge the glass by the video as the glass is certainly better than the video shows.

Warranty & Conclusion

The PA GLx 4-16×50 features a Lifetime Warranty through Primary Optics.

My opinion of the scope is that I would run it. It works. It tracks. It returns to zero. I love the zero stops and locking turrets. I honestly don’t know what more I could ask for or expect at that price point. It looks attractive and like a much more expensive optic. With the lifetime warranty, I don’t really see how you can go wrong with one.

Visit this link to see the Primary Arms GLx 4-16×50 FFP Illuminated Mil Dot

Price: $699

During the video, the wind was pretty gusty. This was a five-shot group I shot at 700 yards with the PA GLx 4-16 after the wind died down.


Brand: Primary Arms

Click Value: 0.1 Mil

Exit Pupil Diameter: Low: 12.20 mm / High: 3.20 mm

Eye Relief: Low: 3.60 in / High: 3.50 in

Field View 100: Low: 23.70 ft / High: 6.30 ft

Focal Plane: First Focal Plane

Illuminated: Full Illumination

Maximum Magnification: 16

Minimum Magnification: 4

Night Vision Compatible: Night Vision Compatible

Objective Diameter: 50mm

Reticle: MIL-Dot

Reticle Type: MRAD

Total Elevation Adjustment: 25 MIL

Total Windage Adjustment: 25 MIL

Tube Diameter: 30mm

PRICE: $699

The scope comes with Butler Creek scope cap covers.
Image through the scope. Don’t judge clarity as the actual view through the scope is better than what I could capture with a photo.
Visit Primary Arms

About the author: True Pearce is the Managing Editor at GunsAmerica. He’s a competitive shooter, hunter, instructor & attorney. You can see and follow his adventures on Instagram. @true1911

{ 4 comments… add one }
  • Aron Tommila September 2, 2020, 6:22 am

    Thank you for your review. I appreciate the time you spent and your candid opinion.

  • Wade Gillis August 24, 2020, 8:42 pm

    I want to challenge ya to review the Blackhound Optics 4×14×44, at $299 it brings a ton of bang for the buck!

  • Ricky Darrell Allison August 24, 2020, 11:10 am

    I’m a 5th Marine Scout/Sniper(early RVN). Couldn’t you have scoped in on something other than a herd of wild horses??? Even I would have picked a more appropriate target!!! Like your photographer, for instance!

  • me August 24, 2020, 9:49 am

    Where is it made?

Leave a Comment

Send this to a friend