Glock MOS optic footprint and plates

How to identify a Glock MOS slide without a caliper

Take the small cover plate off the rear of the slide and look into the recess. You are checking one thing: is there a footprint down there, or a pocket for a plate?

1. A plate pocket is flat and blank. A MOS slide gives you a rectangular recess with two screw holes and no raised features inside it. This dataset records the Glock MOS cut as 2 screws and 0 recoil lugs, which is the signature of a plate pocket: the screws hold a plate down, and the plate, not the slide, carries whatever bosses the optic needs (inside.safariland.com).
2. A milled footprint has raised bosses. If you can see posts or sockets standing proud inside the cut, the slide is milled for an optic pattern directly and no plate belongs in it. Two forward bosses is RMR; four at the corners is RMSc, DeltaPoint Pro or Docter (optics-trade.eu).
3. Check what came in the box. A MOS pistol ships with a set of adapter plates and the screws for them. A direct-cut pistol ships with a cover plate and nothing else. If you have a bag of numbered plates, you have the plate system (all4shooters.com).

The name on the slide is not the tell. Two Glocks in this dataset are marked MOS and are not on this system at all: the 43X MOS and the 48 MOS are cut RMSc in the slide, with no plate involved (swampfoxoptics.com). That is 2 of the 18 Glocks here. The other 16 are the plate system, and the difference is worth 54 optic pages, so settle it by looking into the cut rather than by reading the slide.

Pattern and dimensions

What this dataset publishes for the Glock MOS system today:

Property	Value	Source
Kind	Plate system, not a footprint	dataset
Mounting style	Proprietary plate	dataset
Plate retention screws	2	dataset
Recoil bosses in the slide cut	0, the plate carries them	dataset
Pistols on the system	16 of 196	dataset
Factory plates recorded	4, presenting RMR, RMSc, DeltaPoint Pro and ACRO	opticsplanet.com
Optics that mount with no plate	1	holosun.com

Plate pocket dimensions, screw thread size and screw spacing are not published here, and neither is the full factory plate numbering. Only one plate in this dataset carries its number, adapter 01, the RMR and SRO plate; the other three are recorded by what they present rather than by a part number. The rule on this site is to print a null rather than a guess, so until a Glock plate drawing is read into the dataset, match a replacement plate by part number against your own pistol rather than by the descriptions here.

One more limit worth stating plainly: this dataset records one Glock MOS system and does not separate Gen4 from Gen5 plate sets. 5 of the 16 pistols here are Gen4 MOS models, including the 35 Gen4 MOS (us.glock.com), and they carry the same 4 plate paths as the Gen5 guns. Confirm the plate part number against your generation before buying, because the pattern the plate presents is what this dataset tracks, not which pistol each physical plate drops into. The same caution applies to the two Glock 47 records held here, “47 MOS” and “47 Gen5 MOS”, which are very likely the same pistol under two spellings and are counted separately in the 16.

Look-alikes that will not interchange

MOS against RMR. The most common query shape on this page, and the answer is a category error rather than a comparison. RMR is a footprint: two screws, two forward bosses, the optic bolted down to the slide. MOS is a hole in the slide that a plate sits in. A MOS Glock gets to the RMR pattern through adapter 01, which presents RMR and SRO (opticsplanet.com). Without that plate the slide has no footprint. The full RMR optic list lives on the RMR hub.

MOS against the 43X and 48 MOS slides. Covered above. Same three letters, an RMSc cut instead of a plate pocket.

MOS against the other factory plate systems. SIG P320 X-series, S&W M&P CORE, FN 509, Walther PDP 2.0, Canik METE and Taurus TORO all work the same way and none of their plates fit a Glock. A plate is cut for one pocket. The systems differ in which footprints their plates present, which is the whole reason the optic you can buy depends on the pistol you own.

MOS against a rail mount. If your optic clamps sideways onto a groove with a cross bolt instead of bolting down through its own body, it is an ACRO or Holosun 509T interface optic (optics-trade.eu). ACRO pattern optics do reach MOS, through the ACRO plate. The 509T interface does not appear in the MOS plate set.

How a plate gets you to a footprint

In words, a plate path works like this. The slide is milled for a proprietary pocket that is not a footprint at all. A plate drops into that pocket and its top face carries a real footprint. Fit the plate that presents RMR and the slide behaves, for optic-buying purposes, like an RMR slide. Fit the RMSc plate instead and the same slide behaves like an RMSc slide. The pistol did not change; the interface on top of it did.

The 4 factory MOS plates recorded here, and what each one opens up:

• Adapter 01, presenting RMR and SRO: 33 RMR optics, the deepest optic bench of any pattern in this dataset, from 7 brands.
• The RMSc plate: 30 RMSc optics from 12 brands, the widest brand spread of the four.
• The DeltaPoint Pro plate: 15 DPP optics from 5 brands.
• The ACRO plate: 5 ACRO optics, every one of them an enclosed emitter design.

All four are recorded from the same plate guide (opticsplanet.com), and the table further down this page lists each plate with its sources.

Those four groups do not overlap: no optic page appears on two of them, so the four paths sum exactly to 83 optics. Add the one optic that needs no plate and a MOS Glock reaches 84 of the 100 optic pages in this dataset, from all 16 optic brands it holds. A SIG P320 X-series pistol reaches 85, and the overlap is smaller than that one page suggests: the P320 carries a Docter plate and a C-More STS plate where MOS carries an ACRO plate. MOS trades the 6 Docter optics and the 1 C-More STS optic for the 5 ACRO ones, which is a loss of two optic pages and a gain of 5 enclosed emitter options.

Counted by enclosed emitter optics, that trade is the one that matters. A MOS Glock reaches 21 of the 27 enclosed optics here. A P320, a Canik METE or a Springfield AOS pistol reaches 15. MOS is also the largest of the 9 plate systems with an ACRO path: 16 of the 80 pistols that reach ACRO through a plate are Glocks.

A plate costs you height over the bore and one more interface that can loosen. It is still the only way onto 83 of those 84 optics.

The one optic that needs no plate

The exception is worth knowing before you buy a plate at all. The Holosun SCS-M-GR is built for the MOS pocket itself, so it drops into the cut and bolts down with no adapter underneath (holosun.com). It is the only optic in this dataset recorded as a direct fit on this system, and it fits all 16 of the MOS pistols here.

Two of the 15 plate systems in this dataset have an optic like that, and both are Holosun SCS models: this one, and the PDP version on the Walther PDP 2.0 system. Everything else on every other plate system goes through a plate. Note also what the SCS is not: it is an open emitter sight, so if an enclosed emitter is the requirement, the no-plate route is closed and the ACRO or RMSc plate is where to look.

What a MOS Glock cannot mount

84 of 100 leaves 16 optic pages out of reach, and they fall into five clean groups. This is the part most compatibility charts skip.

• 6 Docter pattern optics. No MOS plate here presents Docter, although 10 other plate systems have a plate that does. This is the expensive gap, because the group includes the Vortex Venom and Viper (egwguns.com) and the Burris FastFire 3 (burrisoptics.com). If you already own one of those, no factory MOS plate here will mount it.
• 5 Holosun K pattern optics. The K pattern is a compact carry standard with 26 pistols cut for it directly and exactly 1 reached through a plate anywhere in this dataset (opticsplanet.com). No MOS plate presents it.
• 1 pistol-specific optic, the PDP version of the SCS, which fits the Walther pocket and not this one.
• 1 C-More STS pattern optic, reachable through four other plate systems in this dataset, the Taurus TORO kit (shoptaurus.com) and the SIG P320 X-series, Canik METE/TP9 and Ruger factory plate systems (outerimpact.com). No MOS plate presents it.
• 3 optics that currently fit no pistol at all in this dataset, so their absence here says nothing about MOS.

How to choose a MOS plate and optic

No prices on this page, and no rankings the data cannot support. What the data does support:

• Choose the plate before the optic, not after. The plate decides the footprint, and the footprint decides the list you are shopping from: 33, 30, 15 or 5 optic pages. Picking the optic first and then hunting a plate is how people end up with a Docter pattern sight and no way to mount it.
• Widest choice: the RMR or the RMSc plate. RMR gives the longest list at 33 pages, though Holosun alone accounts for 16 of them. RMSc gives 30 pages from 11 brands, the best spread if brand choice matters more than raw count.
• Enclosed emitter: the ACRO plate is the shortest path. All 5 ACRO optics are enclosed. The RMSc and DPP plates reach 7 and 5 enclosed options respectively, and the RMR plate reaches 3.
• No plate at all: exactly one option, the SCS above.
• Check the optic page, not the brand. Every optic page lists the pistols it fits and links the source for that claim, and several brands sell the same model in more than one footprint.

Nothing here is verified against a physical sample. Every fit claim on this page is sourced research, a manufacturer or retailer page recorded against the record it supports, and no Glock plate drawing is yet among those sources. Confirm against your own pistol before you spend money.

Where to go next

• The full chart: all optic footprints and plate systems.
• The long form article this hub owns: Glock 19 Gen 5 MOS red dot compatibility.
• Why a plate is needed at all: do you need an adapter plate?
• The two patterns most MOS owners choose between: RMR footprint guide and RMSc footprint guide, side by side in RMR vs RMSc.
• MOS pistols: Glock 19 Gen5 MOS, 17 Gen5 MOS, 26 Gen5 MOS, 45 MOS, 47 MOS, 34 Gen5 MOS, 20 Gen5 MOS.
• The two Glocks that are not on this system: 43X MOS and 48 MOS.
• The same problem on other pistols: S&W M&P CORE, FN 509, HK VP9 OR, CZ P-10 OR.