Gear Review: Primary Arms SLx RS-10 Red Dot Sight

If you’ve seen a lot of pistol red dot reviews around here recently, it’s because of their increased popularity and the number of manufacturers that are adding to and updating their lines to meet the demand. Primary Arms has been known for good, affordably-priced optics for years and their SLx RS-10 1×23 3 MOA red dot carries on that tradition.

Primary Arms SLx RS-10 red dot sight

The RS-10 is the first red dot sight Primary Arms has designed entirely themselves. They’ve given this micro red dot pretty much everything the average pistol owner wants in an optic for their defensive carry pistol and they’ve kept the price very reasonable for everything you get.

Primary Arms SLx RS-10 red dot sight

Primary Arms includes a lot in the box. In addition to the RS-10 itself — which uses the very popular RMSc/Docter mount pattern — and the usual mounting screws and hardware, PA throws in a low profile Picatinny mount, a GLOCK MOS mounting plate and a rubber dust cover.

Primary Arms SLx RS-10 red dot sight

The Pic mount is a nice add-on and lets you attach the RS-10 to a rifle or shotgun.

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The best red dot designs allow you to access the battery without having to un-mount the sight. That way you don’t have to mess with Loctite, torqueage, and re-zeroing. But that can be difficult in sights small enough for micro-compact pistols like the SIG P365, the Springfield Hellcat and others.

Primary Arms SLx RS-10 red dot sight

Unlike a lot of red dots that load the battery from the top, the RS-10 is designed with a lateral access door on the side. That solves the problem of changing batteries without un-mounting and re-mounting. The only problem is…getting the CR2032 battery out of there.

The best method I’ve come up with is shoving a round wood toothpick in the forward side of the battery compartment and sort of jimmying it out of there. It’s kind of a PITA, takes a minute or so, but it’s doable.

Pro tip: make sure you load the RS-10 with a fresh battery, close the door and don’t worry about it for a couple of years at least.

Primary Arms SLx RS-10 red dot sight

Primary Arms rates the battery life at 40,000 of use in typical conditions and brightness. That’s about 4.5 years for those of you who are numerically challenged. On top of that, the RS-10 has what PA calls an autolive function (AKA “shake-awake”) that shuts it down after about three minutes of inactivity so that will extend your battery life.

If you see a ding or two on the RS-10 in the pics here, that’s because I dropped it. On concrete. The good news is, no micro red dot sights were harmed in the production of this review. The RS-10’s 7075 aluminum housing did its job nicely and protected the sight. I remounted it on the FN-509 you see here and it worked just fine.

I also stuck in in the freezer for a few hours and dunked it in water. Once I dried it off, everything worked just as it should.

Primary Arms SLx RS-10 red dot sight
Lots of optic makers like to use Torx screws for the windage and elevation adjustments on their red dots. They then include a small Torx wrench so you can zero your sight. Primary Arms gave the RS-10 standard flat-blade screws so you can adjust them with the tip of your pocket knife, the edge of a cartridge case, or lots of other readily available stuff. It adjusts with tactile 1 MOA clicks.

I also took it from a 70-degree air-conditioned house into my blazing Texas triple-digit backyard (and back again) a number of times. The coating on the lens kept the RS-10 fog-free.

I mounted the RS-10 on my FN 509 Midsize tactical with one of FN’s included MRD plates to raise it slightly. That lets it co-witness perfectly with the suppressor-height sights on the pistol. If you’re mounting the RS-10 on a gun with standard height sights, the RS-10 is low profile enough to co-witness with just about any standard height sights.

Primary Arms SLx RS-10 red dot sight

Another pleasant surprise is how much edge-to-edge clarity the RS-10 shows. Aspherical lenses give you true clarity across the full field of view, they’re more expensive. That’s why most red dot makers don’t go to the expense of using them.

Mangin lenses are more often used and that means you tend to get some distortion around the edges…more on some red dots than others. The RS-10’s mangin lens is better than most I’ve seen, producing better edge-to-edge clarity than many red dot’s I’ve used from brands you know well costing significantly more.

Primary Arms SLx RS-10 red dot sight
Like just about everything red dot sight, there’s a slight blue tinge to the view through the RS-10’s 23mm window.

With eleven brightness setting (including one that’s night vision compatible) the RS-10 works as well outside in bright, harsh noontime daylight as it does indoors. I tried it with the sun both behind and in front of the sight and got a clear, useable view in all conditions.

Again, Primary Arms has done something very impressive here. They’ve designed a tough, well-built red dot sight that gives most pistol carriers everything they need and they’ve done it at a price just about anyone can afford.

Specifications: Primary Arms SLx RS-10 Red Dot Sight

Reticle 3 MOA dot

Optic width: 23mm

Mount: RMSc/Docter

Auto On: Yes

Weight 1.07 Oz

Battery Life: 40,000 hrs

Battery: CR2032 

Housing: Anodized 7075 Aluminum

Night Vision Compatible: Yes

Made in: China

Ratings (out of five stars):

Clarity * * * *
Very good, particularly for a mangin (non-aspheric) lens. Edge-to-edge clarity is better than many red dots costing $100 more. There’s the usual slight blue tint.

Reliability * * * * *
I dropped it on concrete. I froze it. I dunked it. It’s still working. For a budget-priced red dot sight, that’s very good.

Ease of Use * * * *
The SLx RS-10 has everything you want. Simple, standard flat blade zero adjustments. Up and down brightness adjustment on one side. Battery door on the other. One star off for the hassle of getting the batter out, but with auto on and 40,000 hours of rated battery life, you won’t have to deal with it often.

Overall * * * * ½
The Primary Arms SLX RS-10 IS an exceptionally good value in a red dot sight. It’s exactly what the great majority people want in a micro red dot for their carry pistol — a good, clear red dot that’s build well, reliable and doesn’t drain their ammo budget too much.

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