red dots

Primary Arms GLx MD-21

Primary Arms GLx MD-21

ACSS CQB Review

  It seems like nowadays everyone is making some sort of tube style red dot. Primary Arms is no different, except they seem to always be upgrading or bringing out new styles. The Primary Arms GLx MD-21 is one of their new red dots and it has some features not usually seen on the current generation of red dots. 

  This GLx MD-21 is in Primary Arms’ mid tier optics line. What does that mean for you? You get clearer glass with less tint, a multi reticle system, a solar fail safe, and multiple mounting options. Since the GLx MD-21 is a projected reticle, you may still have some starring out effect if you have an astigmatism. I have one and the MD-21 gives me a pretty clear sight picture. Or at least better than some other red dots that I personally have. 

  The GLx MD-21 is a tube style red dot. This makes it ideal for carbines or AR style pistols. Having 21 mm lenses gives it a decent field of view, Everything needed to adjust the little red dot is also placed around the optic. On the right side is the battery compartment for the CR2032 battery along with the horizontal reticle adjustment. On top is the solar panel and the vertical reticle adjustment. The reticle adjustments are large, have really good clicks, and adjust in 0.5 MOA clicks. I like the finer adjustments on the MD-21 over the 1 MOA ones found on other red dots. On the left side of the optic are the multi-use, soft touch, buttons. They are quite large and labeled “+” and “-”. Then on the bottom is a standard T1/T2 footprint for mounting. Primary Arms includes two mounting options with the MD-21. They are 1.41" or 1.535" mounting heights. I used the 1.41” one and it worked great. If you want something different, there are a bunch of other options available for the T1/T2 footprints. 

  Other features of the MD-21 abound. Of course it has Primary Arms’ autolive feature that turns the reticle on when moved and off when idle. This is also the first Primary Arms solar failsafe red dot. The solar failsafe helps with battery life and also will let the red dot function with a dead battery. Yes, it works without a battery also, at least if there is enough ambient light. Also included in the GLx MD-21 is a new super bright LED. You can probably see the reticle from space if the brightness is turned all the way up. Speaking of brightness, it has 12 levels and is night vision compatible. 

  The MD-21 doesn’t just have a red dot reticle. It is available with Primary Arms’ ACSS CQB reticle, which is what they sent me for this review. The ACSS reticle is a horseshoe style with a center chevron and bullet drop marking below it. The bullet drop compensation is made for 5.56 and .308 out to 600 yards, but it also works with other calibers. I like having the bullet drop compensation, but in a 1x optic, it is really small and hard to make out. If you were to run a magnifier with it, it would work much better. With that said, the GLx MD-21 also has the ability to use only portions of the ACSS reticle. By holding down the + or - button, it will cycle through reticle options. You can have the full ACSS CQB reticle with the bullet drops, just the chevron and bullet drops, just the chevron (basically a dot style reticle), or the horseshoe and chevron (my favorite). Having the ability to choose which reticle you want is great. When adjusting the brightness on the MD-21, the reticle will flash when you reach its maximum or minimum brightness. I like this function when in the bright sunlight, that way I know when to stop pressing buttons.

  I ended up mounting the MD-21 on the Global Monolith rifle. For some reason I tend to mount different optics on this rifle, probably because I like shooting the rifle and it makes testing out optics easier. Either way, I like the MD-21 on it. This little red dot is super bright, which works great in the bright sunlight. Even though the BDC part of the reticle tends to blur together for me, it is still useful if I want to shoot past 100 yards. The solar failsafe works so well that I actually did some shooting with the battery removed. The large buttons make it easy to adjust the brightness, or even the reticle. I really liked how well the MD-21 worked for my application. But I am also a fan of 1x optics.

  Primary Arms did a great job with the GLx MD-21. I was hard pressed to find anything bad with the MD-21. If you like red dot style optics, it is definitely worth looking into. The solar backup and reticle options make this a great option in the red dot game. If you just want a standard “dot” version, they have that too. You can check out the GLx MD-21 over at PrimaryArms.com

Firearms Insider Reviews - Key Points

Claim to Fame:

Quality Solar Red dot with ACSS reticle

Target Market:

Anyone wanting a solar red dot

Features, Benefits, and Specifications of this product:

  • Solar Failsafe and Autolive technology extends battery life 

  • Fully multi coated lens 

  • Side mounted push button controls 

  • Ultra bright ACSS-CQB reticle with 4 selectable modes 

  • Night vision compatibility 

  • Shockproof and waterproof aluminum construction 

  • Black anodized finish 

  • Includes Low mount and Absolute Cowitness mount with spacer (1.41" or 1.535" Height)

  • Standard T1/T2 microdot footprint

  • Accessory Attachment: M1913 Picatinny

  • Battery Type: CR2032 3V Lithium Coin

  • Brightness: 12 Settings

  • Click Value: 1/2 MOA

  • Finish: Hardcoat Anodized

  • Night Vision Compatible

  • Reticle: ACSS CQB

  • Warranty: Lifetime

  • Weight: 5 oz.

What other aesthetic options or finishes are available?

Dot only version   

What others are saying?:

Evan: 4 out 5 stars at PrimaryArms.com

Nice Optic

Optic is nice but I am a little disappointed with the chevron. The chevron is too small to make out so it just looks like a dot. I'll have to view it under some magnification to see how I like it. The horseshoe is pretty sharp even with my astig. Brightness settings are awesome although I can't speak on the night vision settings because I don't have night vision to test them. Build quality seems solid and it has some weight to it. Overall I'm happy with this optic and can't wait to run it.

Link to other reviews:

704 Tactical

Price point:

MSRP = $219.99

Retail = Same

I need it now! Availability:

Primary Arms or your local retailer

Our Rating:

Pros:

  • Solar backup

  • Multi-reticle

  • Standard T1/T2 mount

  • Clear reticle

  • Lightweight

  • Comes with various height mounts

  • Autolive on/off

Cons:

  • Reticle is small and hard to see

Score: 8.50 Great

Favorite Link:  Global Ordnance Monolith Review