Best Red Dot Sight for a Glock: How to Choose

By Accufire Editorial Team · June 7, 2026

You picked up a Glock MOS — or you're about to — and the only real question is which red dot mounts to it and runs reliably on a carry gun. The best red dot for a Glock is one that matches your slide's footprint exactly — the RMR pattern on full-size MOS models, the smaller RMSc pattern on slim cuts — with a fast 3 MOA dot, dependable power, and a mount you can co-witness. Get the footprint right first; everything else is preference. Here's how to choose, and where Accufire's PCO sights fit.

First, confirm your Glock's optic cut

Glock's factory red-dot system is called MOS, for Modular Optic System. A MOS slide ships milled for an optic with a set of adapter plates; you fit the plate that matches your optic's footprint, then mount the sight to the plate. Full-size MOS models — the G17, G19, G45, and G34 MOS — are built around the larger footprints, with the Trijicon RMR pattern being the most common. Slim MOS models like the G43X MOS and G48 MOS are cut for the smaller RMSc footprint instead. A standard non-MOS Glock isn't drilled for an optic; to mount one you'd have a gunsmith mill the slide or swap to an optic-cut aftermarket slide. The single most expensive mistake is buying a sight your slide can't accept — confirm the cut or plate first.

What to look for after footprint

Dot size. A 3 MOA dot is the default for a reason: fast enough to find under stress, fine enough for accurate fire at typical pistol distance. Accufire's PCO Reflex and PCO Mini both use a 3 MOA dot. If you want more on the trade, see 2 MOA vs 6 MOA dot size.

Battery and reliability. On a carry gun, reliability is the whole point. Look for a sensible battery system and a sight built for firearm use; the PCO Reflex uses a top-loading battery, while the PCO Mini uses a side-loading tray so you don't have to dismount the optic to change cells.

Co-witness. Decide whether you want your iron sights visible through the optic window as a backup. That usually means taller suppressor-height or optic-height sights — see our breakdown of absolute vs lower-1/3 co-witness.

How to choose: the honest shortlist

There's no single "best" Glock optic — only the right footprint and the right size for your use. Holosun's 407C/507C and enclosed EPS Carry, the Trijicon RMR and RCR, and SIG's Romeo lineup are all proven, popular picks across a range of prices. Accufire's position is a manufactured-not-white-labeled open reflex at an accessible price. Here's where the PCO sights land for a Glock:

Choose the PCO Reflex if your full-size MOS plate is RMR-pattern; choose the PCO Mini if your slim slide is cut for RMSc. Match the footprint, mount to spec, and zero.

Honest limitations

A few honest notes. The MOS plate system adds a layer between the optic and the slide, so plate fit and screw torque matter — follow Glock's and the optic maker's instructions and use the correct screws. An open reflex leaves the emitter exposed, which is fine for everyday carry but less sealed than an enclosed optic for the harshest conditions. And any battery optic can fail, which is exactly why a co-witnessed set of iron sights earns its place on a defensive Glock. None of that is a reason to skip a dot — just reasons to set it up correctly.

Frequently asked questions

Which Glocks can mount a red dot?

Factory MOS Glocks like the G17, G19, G45, and G34 MOS come milled for an optic and ship with adapter plates that fit common footprints. Slim models such as the G43X MOS and G48 MOS are cut for the smaller RMSc footprint. A standard non-MOS Glock can be milled by a gunsmith or fitted with an optic-cut aftermarket slide. Always confirm your slide before buying.

What footprint does a Glock red dot use?

It depends on the model. Full-size MOS Glocks use the MOS plate system, where a plate matches your optic's footprint, often the Trijicon RMR pattern that the Accufire PCO Reflex uses. Slim MOS Glocks like the 43X and 48 are cut for the smaller RMSc footprint that the Accufire PCO Mini uses. Match the optic to the plate or cut your slide actually has.

Do I need suppressor-height sights to co-witness a Glock optic?

To co-witness, your iron sights must be tall enough to appear in the optic window, which usually means taller suppressor-height or optic-height sights. Co-witnessing lets you aim with the irons if the dot ever fails. It is optional but recommended for a carry or defensive pistol; many range guns run the optic alone.

What dot size is best for a Glock?

For general carry and range use a 3 MOA dot is a popular all-round choice, fast to find yet precise enough for accurate fire. The Accufire PCO Reflex and PCO Mini both use a 3 MOA dot. Larger dots are quicker up close, while smaller dots favor precision at distance.

Is the Accufire PCO good for a Glock?

The PCO Reflex fits full-size MOS Glocks through an RMR-pattern plate, and the PCO Mini fits slim RMSc-cut slides like the 43X and 48. Both are open reflex sights with a 3 MOA dot, a side or top battery, and an accessible price. Confirm your slide's cut or MOS plate footprint first, then mount and zero it.

Match the footprint, pick a 3 MOA dot, and co-witness if it's a carry gun — that's a Glock red dot done right. For more, see our best red dot for a pistol guide, the best budget red dot, and the full red dot sights buyer's guide.