Holosun SCS-MOS

The SCS-MOS attaches directly to a Glock MOS slide with no adapter plate in the stack, which is the whole point of the model. Holosun specifies the two supplied screws at 15 inch-pounds, or 1.7 Nm.

Two fitment facts matter before you order. The MOS mounting pattern this sight uses covers Glock MOS pistols except the 43X MOS and the 48 MOS, which Holosun calls out by name as excluded. And Holosun recommends pulling the slide off the frame before the optic goes on, which gives you a flat surface to work against and keeps a dropped screw out of the fire control group.

Elevation lives on the top-rear section of the housing and windage on the right side toward the rear. Both take the flat tipped end of the included tool in the turret slot. On the SCS-MOS-GR each click is 1 MOA, or about 1 inch at 100 yards, which puts a click at 1/4 inch at 25 yards. Note that the P320 and Carry models in the same family are 1.5 MOA per click, so click math borrowed from a friend's SCS may not be your click math.

Holosun zeroes the sight at the factory to approximately 25 yards. That is a starting point, not a zero: it knows nothing about your pistol or your load. Total adjustment range is plus or minus 30 MOA, which is noticeably tighter than the 50 MOA most pistol dots offer, so a cut that is not square to the bore eats a larger share of your available travel.

One function button on the left side of the housing does everything on the SCS. A 3 to 5 second press powers it up, and every reticle change and the power-off are the same press-and-hold walking through a fixed order: circle dot, dot only, circle only, off. Default on power-up is a 2 MOA dot centered in a 32 MOA circle with four positioning points, and that circle subtends about 32 inches at 100 yards.

Brightness is fully automatic. There is no manual brightness ladder on this sight: a photosensitive sensor reads ambient light and sets reticle intensity, with auto mode holding a floor between settings 4 and 5 and ranging up to 12. Holosun states plainly that auto mode is not designed for night vision use. What you do get is a manual override for the one case automation handles worst, which is a bright target against a dark backdrop.

The SCS runs a sealed internal rechargeable cell that is not removable, kept topped up by the solar panel. The photovoltaic cells are always working, either charging the cell, powering the reticle, or both depending on light.

Every time the sight powers on, a sensor checks charge state for 10 seconds and reports low charge by blinking. Below 20 percent you get one flash every one to two seconds for a 10-second cycle; below 10 percent, two flashes; below 5 percent, three flashes. Recovering from a fully flat cell takes about 50 hours of bright light, which Holosun defines as 10,000 lux or better, a cloudy day outdoors. The sight stays usable during that recovery, because light that bright powers the reticle and charges the cell at the same time.

The consumption math is why this rarely matters. Ten hours of circle-dot use in the most demanding case draws 12 microamp-hours, while one hour outdoors puts back 100. Holosun's expectation is that the system works until the cell ages out, which they put at 10 years and up.