Glock 43X MOS and 48 MOS: which micro red dots fit

The 43X MOS and 48 MOS have a slide cut for the Shield RMSc footprint, the smallest common red-dot pattern, and a dot on that footprint bolts straight to the slide with no plate. That makes them the easiest Glocks to put a dot on and the ones with the fewest choices, because the RMSc footprint rules out the larger optics used on standard-frame pistols. This guide lists the dots that fit, the ones that fit with a plate, how to mount and zero, and the sights that work with a dot.

The footprint

The RMSc pattern uses two screws and two recoil bosses in a compact rectangle. Glock's cut has the bosses and the screw holes; the dot sits directly on the slide. Anything on a different footprint, such as the RMR, the Docter or the Aimpoint ACRO, does not fit without milling. Dots described as RMSc, Shield, K-footprint or Holosun K fit.

Dots that mount directly

Holosun 407K and 507K: the most common choice. Aluminum housing, side-loading battery, shake-awake, a 6 MOA dot on the 407K and a multi-reticle on the 507K. Sold in a version with a Glock MOS adapter plate for the standard footprint and a version without; the plain 407K/507K mounts to the slimline cut directly.
Holosun EPS Carry: an enclosed emitter on the K footprint, taller and heavier, immune to rain and lint on the emitter. Fits directly.
Shield RMSc and SMSc: the original footprint, lighter than the Holosun, polymer lens on the base RMSc and glass on the RMSc glass edition. Fits directly.
Sig Sauer RomeoZero and RomeoZero Elite: polymer housing, very light, RMSc footprint. Fits directly.
Swampfox Sentinel: RMSc footprint, aluminum. Fits directly.
Crimson Trace CTS-1550: RMSc footprint. Fits directly.

Dots that need a plate

The Trijicon RMRcc uses its own footprint, narrower than the RMR, and needs the Trijicon adapter plate for the Glock MOS slimline cut; the plate raises the dot a little. The Leupold DeltaPoint Micro clamps to the rear dovetail and ignores the MOS cut entirely, which is a route to a dot on a non-MOS 43 or 48 as well. Anything on the full RMR or Docter footprint needs a milled slide from an aftermarket maker.

Mounting

Remove the cover plate with the small screws, clean the cut with alcohol, and set the dot on the bosses. Use the screws that came with the dot or with the pistol, at the length the dot maker specifies; a screw that is too long bottoms out in the slide and does not clamp, too short strips the threads. A drop of blue thread locker, torque to the maker's figure with an inch-pound driver, usually 12 to 15 inch-pounds, and let the locker cure overnight. Witness marks on the screw heads show you if they move.

Zero

Zero at 10 yards from a rest, then confirm at 25. With a slimline pistol most shooters set the dot to sit on the point of impact at 10 and accept a small offset at 25. Move the dot in the direction you want the impact to move; the adjustment clicks are listed on the dot. Shoot a group of five after each change, not one round. Recheck the zero after the first 200 rounds and after any drop.

Sights with a dot

The factory sights on the MOS pistols are standard height and sit below the window on most dots; that is fine for a carry pistol where the dot is the sight. Suppressor-height sights that show through the window are available in the slimline dovetail from the major sight makers; they let you shoot with irons if the dot fails and they help find the dot on the draw. Check that the front sight clears the rear of the dot housing before ordering.

Learning the dot

A red dot on a small pistol is a skill, not a purchase. The dot is found by presenting the pistol to the same place every time, not by hunting for it, and the drill is dry: draw, present, see the dot, a hundred times a day for a couple of weeks. A large dot, 6 MOA or the Holosun circle, is easier to find than a 3 MOA dot on a carry gun. Clean the lens with a soft cloth, keep the emitter clear of lint, and replace the battery on a schedule, once a year, even if it is not dead.

Batteries and weather

Every dot on this list runs on a coin cell, a CR1632 on the Holosun K models and a CR2032 on most of the others, and the side-loading tray on the Holosun means the dot stays zeroed through a change. Change the battery on a fixed date each year. Open-emitter dots collect lint in a pocket-adjacent appendix holster and rain on the emitter blanks the dot for a moment; a wipe with a fingertip fixes it, and an enclosed emitter avoids it. Fogging in cold-to-warm changes clears in a minute; an anti-fog wipe on the lens helps.

Holsters for a dotted slimline

Most current Kydex holsters for the 43X and 48 are cut to clear an optic; older holsters may not be. Buy a holster that names the optic cut, and if you add a light to the MOS rail, buy a holster for that light. The carry setup guide covers the combinations.

A short list

For most owners: a Holosun 407K or 507K, suppressor-height sights, a holster cut for the optic. For rain and lint: the EPS Carry. For the lightest package: a RomeoZero or Shield RMSc. For an existing Trijicon collection: the RMRcc on its plate. For a non-MOS 43 or 48: the DeltaPoint Micro or a milled slide. See how the pistols themselves compare in the slimline comparison. Browse micro red dots and slimline sights; they ship to your door.

General information, not legal advice. Current as of September 2026. Laws change; check the official source before you act.