Travis Olander 03.28.23
Glock’s “MOS – Modular Optical System” pistols provide something that was lacking in the Austrian gun maker’s arsenal for too long: factory slide cuts with red dot optic compatibility for a wide range of optic footprints. Gone are the days of sending out your factory Glock slide to a machine shop for a CNC trim. The G19 MOS includes four red dot plates that bolt to its pre-cut slide. Of all the available micro red dots, I chose the Holosun 507C “X2” MRS. It’s a kickass little solar-powered reflex sight that punches above its weight, giving much more expensive MRSs (like the Trijicon RMR) a run for their money. Here’s a quick review and install of the Holosun 507C X2 MRS Red Dot.
Holosun 507C X2 MRS: Quick Specs
The X2 MRS advertises up to 50,000 hours of battery life – but that’s a bit misleading. When exposed to a light source, the small solar panel integrated into the glass housing charges and powers the LED.
It’s not a gimmick, either. As soon as I popped it on my G19 and shone it under a window, the LED got wicked bright and I had to turn down the settings. It works with indoor lighting well enough, too.
There are 12 brightness settings – 10 for daylight and 2 for NVGs – with that 50k hour battery life estimated on brightness setting “6”. The battery’s housed in a waterproof, O-ring sealed compartment under the glass, operating on a CR1632 which is, thankfully, included in the box.
The housing is machined from a single piece of 7075-T6 aluminum and it sports what looks and feels to me like a typical Type 3 Hardcoat anodized finish, offering a soft matte black coating. It pairs nicely with the factory Glock slide’s own black “Tenifer” (nitrate) treatment.
Holosun 507C X2 MRS Red Dot: Mounting and Bolts
Also in the box is a T-10 Torx and flathead key, used for screwing in the mounting bolts and for removing the battery compartment cover. Holosun includes mounting bolts of various lengths – you’ll need to make sure the ones you pick don’t have threads that are too long:
If you’re mounting it to a Glock slide, long threads have a chance of running into the extractor plunger and firing pin spring. Make sure you pick the right lengths (there should be just 2 to 3 threads poking out from the bottom of the optic).
If you’re running a G19 MOS, you’ll need adapter plate “02” provided with the pistol. Only use the bolts provided by Holosun to mount the optic to the plate; the other bolts provided with the Glock adapter plate are not the correct thread pitch and will cross-thread, damaging the plate.
Holosun 507C X2 MRS Red Dot: Housing & Glass
The X2 is a beefy little optic. The aluminum housing has very thick walls insulating the glass. Rounded corners and subtly chamfered edges provide some extra strength by reducing stress points and sharp bits, which would otherwise chip or roll.
The multi-coated glass does fine indoors and outside. I had no issues with glare or sunspots while running it at my local outdoor range. Inside, the glass provides excellent clarity and contrast in relatively low light.
Holosun 507C X2 MRS Red Dot: MOA Adjustments
The recessed turrets provide nice, clicky, tactile adjustments. The Torx tool should be used to make the adjustments. Each click provides 1 MOA, or 1″ at 100 yards. Total adjustment travel for windage and elevation is +/- 50 MOA.
Holosun 507C X2 MRS Red Dot: Sight Picture
The X2’s sight picture is decent. The thick housing sacrifices a bit of glass real estate, but it’s nothing that hinders open sight alignment nor awareness. The window measures about 0.63″ wide by 0.91″ tall.
I wasn’t able to snap a reliable picture of the red dot, but it’s bright, crisp, and clear. The dot can be adjusted to display both the halo and center dot, or just the dot or halo. The dot itself measures 2 MOA and the radius of the circle measures 32 MOA.
Holosun 507C X2 MRS Red Dot Controls
All of the optic’s controls are built into the two brightness adjustment buttons. To switch the reticle display, you need to depress the MINUS button for three seconds. Obviously, the PLUS and MINUS buttons primarily control the optic’s brightness.
The sight’s operating mode can be switched by holding down the PLUS button: “Auto Mode” allows the unit to operate on solar and battery power, with the reticle automatically adjusting brightness based on sensing (via the solar panel) whether you’re indoors or outside.
In “Manual Mode,” the brightness is controlled by manual adjustments via both PLUS and MINUS buttons.
Sleep Time can be adjusted using the buttons, too. By default, the optic will turn off after 10 minutes of no movement. Sleep Time can be adjusted to, 1 hour, 12 hours, or OFF.
With Sleep Time OFF, the unit must be powered off by holding down both the PLUS and MINUS buttons.
Holosun 507C X2 MRS Red Dot: Final Thoughts
So, is there anything to not like about the X2 MRS? In my opinion – so far, at least, with about 500 rounds down the tube – not really, no. For $299, the Holosun functions beautifully. I was able to dial it in with a laser boresight at 20 yards and it’s held zero through dozens of magazines.
It’s incredibly bright outside at full setting, and the solar panel does a great job of providing automatic adjustments when you switch between indoors and outdoors. The sight feels incredibly tough for its size and price, and it is properly waterproof — evidenced by my getting caught in the back deserts of Utah during a pretty heavy spring thunderstorm while shooting on public land.
Bonus to Holosun for sticking with the popular and widely compatible RMR footprint.
