Most Universal Red Dot Footprint: RMSc Fits 186

Ask which pistol red dot footprint is the most universal and this dataset gives one answer: RMSc, which reaches 186 of the 196 optic-ready pistols on this site, or 94.9%. RMR is second at 117 and DeltaPoint Pro third at 112. Nothing else clears 80.

That answers the question as asked. It is also the least interesting thing in the numbers, because “universal” is three separate questions with two different winners, and the most useful finding inverts the premise: being cut for the most universal footprint gives a pistol the narrowest optic selection in the dataset. A slide milled for RMSc and nothing else reaches 30 of the 100 optic pages. A Walther PDP with a plate pocket and no milled footprint at all reaches 90. Every figure below is recomputed from the published export bundle, version 2026-09-30: 196 launchable pistols, 100 optic pages over 135 SKUs, 24 footprint and plate-system records.

Every pattern ranked by the pistols it reaches

Nine of the 24 records on this site are true footprints, meaning a screw and recoil pattern an optic bolts to. The other 15 are plate systems, which present a footprint through a plate rather than being one. Here are the nine, ranked by total reach across the 196 pistols:

Pattern	Optic pages	SKUs	Optic brands	Milled slides	Via plate	Total reach	Share of 196	Plate systems selling it
RMSc	30	33	12	80	106	186	94.9%	14 of 15
RMR	33	47	7	7	110	117	59.7%	15 of 15
DeltaPoint Pro	15	16	5	2	110	112	57.1%	15 of 15
ACRO	5	5	3	0	80	80	40.8%	9 of 15
Docter	6	6	4	0	55	55	28.1%	10 of 15
C-More STS	1	1	1	0	28	28	14.3%	4 of 15
Holosun K	5	8	1	26	1	27	13.8%	1 of 15
Holosun 509T	2	8	1	0	0	0	0%	0 of 15
Holosun EPS	1	9	1	0	0	0	0%	0 of 15

Four things in that table matter more than the ranking.

The milled and plate columns are separate populations. For all nine patterns, the slides milled for a pattern and the pistols reaching it through a plate do not overlap by a single pistol. A pistol here is either a milled slide or a plate pocket, never both, which is why RMSc’s 80 and 106 add to exactly 186 with no double counting.

RMSc owns the milled column. Its 80 direct cuts are more than the other eight patterns combined: Holosun K 26, RMR 7, DeltaPoint Pro 2, and the remaining five have no factory-cut slide anywhere in the dataset.

RMR and DeltaPoint Pro own the plate column. All 15 plate systems sell a plate presenting each of those two. RMSc is on 14 of 15, missing only Taurus TORO. On plate ubiquity the overall winner comes third.

Two patterns are unreachable. Holosun 509T and Holosun EPS are real footprints carrying real optics, 2 and 1 pages, and not one of the 196 pistols can mount either by any path: no slide is cut for them and no plate presents them. A footprint can exist, carry product, and still be a dead end.

The 100 optic pages collapse into 10 fit lists

Before using the table above to pick an optic, there is a structural fact about this dataset that changes what the question even is. Every optic that shares a footprint fits an identical list of pistols. Not a similar-sized list: the same list, pistol for pistol, verified set by set across all 100 pages.

Pistols the optic fits	Optic pages	Pattern
186	30	RMSc
117	33	RMR
112	15	DeltaPoint Pro
80	5	ACRO
55	6	Docter
28	1	C-More STS
27	5	Holosun K
16	1	Glock MOS
10	1	Walther PDP 2.0
0	3	three patterns with no path

One hundred pages, ten distinct answers. So “which red dot fits the most pistols” is never an optic question here, only a footprint question. The Shield RMSc and the Holosun EPS-CORE fit the same 186 pistols; the Trijicon RMR Type 2 and the Holosun 507C-X2 fit the same 117. Window size, reticle, battery access, durability and price are all live questions between two optics on one pattern. Compatibility is not.

Two rows are oddities worth naming. The pages at 16 and 10 are both Holosun SCS units, the SCS-M-GR and SCS-PDP-GR, built to drop into a specific plate pocket rather than onto a footprint: one fits the 16 Glock MOS pistols, the other the 10 Walther PDP 2.0 pistols, and neither fits anything else. The three at zero are holosun/eps, holosun/aems-macro and holosun/he509t-x2, on the two unreachable patterns above.

RMSc plus RMR is the only pair that covers all 196

If no single pattern reaches everything, the next question is how few patterns it takes. The answer is two, and there is exactly one pair that does it.

RMSc at 186 leaves 10 pistols out. Every one of those 10 is reachable with an RMR optic, so {RMSc, RMR} covers all 196. Tested exhaustively, it is the only pair among the nine patterns that does: all 7 covering combinations of three patterns also contain both of them. Neither is substitutable. Drop RMSc and the other eight patterns together reach 143 of 196, leaving 53 pistols with no path. Drop RMR and the remaining eight reach 191, leaving 5.

The 10 pistols RMSc cannot reach split into three groups, and the reason differs in each:

Pistol	Why RMSc misses it	Optic pages it reaches
Taurus G3 TORO, G3c TORO, G3 Tactical TORO, TX22 Competition	Taurus TORO is the one plate system here with no RMSc plate	55 each
Anderson Kiger-9C Pro, Lone Wolf Dusk 19, Lone Wolf LTD19 V1, Tisas PX-9 Gen3 Duty, Tisas PX9 Gen3 O.R. Carry	milled for RMR only	33 each
Shadow Systems MR920	milled for RMR and DeltaPoint Pro, not RMSc	48

By brand the picture is more lopsided still. The 196 pistols come from 30 makers, and RMSc reaches at least one pistol from 28 of the 30. Only Anderson Manufacturing (1 pistol) and Lone Wolf Arms (2) are shut out completely, all three Glock-pattern slides milled for RMR; three more are partly out of reach, Shadow Systems at 2 of 3, Tisas at 3 of 5 and Taurus at 6 of 10. Direct cuts concentrate further: 25 of the 30 brands have a slide milled for RMSc, and of the five without, Beretta, CZ-USA and Walther are not snubbing the pattern, they simply mill no footprint at all because every optic-ready pistol they have here is a plate system.

The inversion: a universal footprint makes a narrow pistol

Here is the finding that matters most when spending money, and it runs opposite to how the question is usually framed.

Split the 196 pistols by how they mount an optic. 86 have a footprint milled into the slide. 110 have a plate pocket. Then count how many of the 100 optic pages each one can actually reach:

Group	Pistols	Lowest reach	Median	Mean	Highest
Milled footprint	86	30	30	32.5	78
Plate system	110	55	84	84.1	90

The worst plate system here beats every milled slide but one. The median plate-pocket pistol reaches 84 of 100 optic pages; the median milled slide reaches 30.

The largest single block at that floor is the RMSc crowd. 53 of the 196 pistols reach exactly 30 optic pages, and all 53 are slides milled for RMSc and nothing else. The most universal footprint produces the least universal pistols. There is no contradiction: a milled cut is one pattern forever, and RMSc is the pattern with 30 pages on it, while a plate pocket is four or five patterns swappable with a screwdriver.

The rest of the milled population: 26 pistols reach 35, their slides cut for Holosun K as well as RMSc, which adds that pattern’s 5 pages to RMSc’s 30. Five RMR-only slides reach 33. The MR920 reaches 48 on two patterns. One slide reaches 78.

The Ruger RXM is the most capable milled slide here by a wide margin, because Ruger’s own spec sheet for the pistol records it as cut for three patterns at once, RMSc, RMR and DeltaPoint Pro (ruger.com). That stacks 30 plus 33 plus 15 into 78 pages with no plate and no adapter. It still loses to every Walther PDP 2.0 pistol, which reaches 90.

At the other end, the four Taurus TORO pistols sit at 55, the lowest of any plate system, on 4 plates. Taurus’s own TORO announcement states that “Four different mounting plates, along with four different sets of screws and L-Key are included with the G3 T.O.R.O. and G3c T.O.R.O.” (taurususa.com). Four plates in the box is generous. It is the pattern mix that holds the number down: this is the one system with no RMSc plate recorded, and RMSc is the 30-page pattern.

The full ranking of plate systems by what their pistols reach, which is the same number for every pistol inside a system:

Plate system	Pistols	Plates	Optic pages reached
Walther PDP 2.0	10	5	90
Beretta APX A1 / 90-Series	10	5	89
Springfield Echelon VIS	4	5	89
Springfield XD OSP	1	5	89
Walther PDP 1.0	1	5	89
SIG P320 X-series	16	5	85
Canik METE	7	5	85
Ruger factory plate	1	5	85
Glock MOS	16	4	84
Springfield AOS	1	4	84
S&W M&P CORE	14	4	83
FN 509 LPOMS	12	4	83
CZ P-10 OR	7	4	83
HK VP9 OR	6	4	83
Taurus TORO	4	4	55

Five-plate systems cluster at 85 to 90 and four-plate systems at 83 to 84, so the plate count explains nearly all the spread. Taurus is the exception: its fourth plate is C-More STS, a pattern with one optic page on it.

Universal on the shelf is a different ranking

Everything above counts pistols. Buyers also care about the other direction: given a pattern, how much product can you actually choose from, and for how long will it be made? Here RMSc does not win outright.

RMR carries the most product. 33 optic pages over 47 SKUs, against RMSc’s 30 pages over 33 SKUs. On raw selection, RMR is the deepest catalogue in the dataset.

RMSc carries the most brands. Twelve of the 16 optic makers here build an RMSc optic: Shield Sights, Sig Sauer, Riton, Meprolight, Primary Arms, Vortex, Swampfox, Bushnell, Steiner, Burris, Holosun and Crimson Trace. RMR has 7. Four brands are missing from RMSc, and they are the ones with their own patterns to sell: Aimpoint, EOTech, Leupold and Trijicon.

RMR’s depth is concentrated. Holosun alone holds 16 of RMR’s 33 pages and 26 of its 47 SKUs. RMSc’s largest single brand is Shield Sights, the company that defined the pattern, at 7 of 30 pages. If one maker changing direction is a risk you price in, the two patterns look less similar than the page counts suggest.

That concentration produces a result worth stating plainly. Holosun is the largest optic brand on this site, at 27 of the 100 pages and 57 of the 135 SKUs, and exactly one of those 27 pages sits on the pattern that reaches 186 pistols. Its page split is RMR 16, Holosun K 5, Holosun 509T 2, and one each on Holosun EPS, Glock MOS, Walther PDP 2.0 and RMSc. The single RMSc entry is the EPS-CORE family, four SKUs listed on holosun.com. Shopping by brand and shopping by reach pull in different directions here.

One more axis flips the ranking completely. Enclosed-emitter optics, the sealed housings that will not blind on rain or lint, number 27 of the 100 pages. By pattern: ACRO 5 of 5, Holosun K 3 of 5, RMSc 8 of 30, DeltaPoint Pro 5 of 15, RMR 3 of 33, Docter 0 of 6. If an enclosed emitter is a requirement rather than a preference, RMR is close to the worst pattern on the board at 3 pages, and ACRO is the only pattern where every optic qualifies. RMSc still carries the most enclosed options in absolute terms, 8, and 4 of those 8 are flagged verified in this dataset: the Meprolight MPO PRO-S, the Primary Arms CLx Enclosed, the Shield AMS, and the Steiner MPS-C, whose own product page states that it “features an RMSc footprint and an exceptionally low profile” (steiner-optics.com).

How to tell which pattern your slide is cut for

Most guides on this query tell you to count screws and recoil lugs. On this dataset’s own recorded geometry that advice does not work, and it is worth seeing why before you put a caliper on anything.

Four of the nine patterns record 2 screws and 4 recoil sockets: RMSc, DeltaPoint Pro, Docter and Holosun EPS. Between them they carry 52 of the 100 optic pages. Two more record 2 screws and 2 front lugs: RMR and Holosun K, another 38 pages. So 90 of the 100 pages here sit on just two geometric signatures. Counting narrows you to a group of four or a group of two. It never gets you to a pattern.

What does resolve it, in the order worth trying:

1. Decide first whether you have a footprint at all. Look into the slide cut with the cover plate off. A milled footprint has threaded screw holes and recoil sockets cut directly into the slide steel and nothing between optic and slide. A plate system has a wider, deeper rectangular pocket with its own fasteners, into which a separate plate drops. That single look splits the 196 pistols here 86 to 110, and it decides every later step. Manufacturers state it in their own words when you know to look: HK’s VP9 Match page says “the machined optics cut accommodates most popular red-dot pistol sights with one of five available mounting plates” (hk-usa.com), and FN’s 509 Fullsize MRD page describes the “FN Low Profile Optics Mounting System with plate adapters for direct mounting of most major pistol red dot optics” (fnamerica.com).
2. If it is a plate system, stop measuring and read the plate. The footprint is a property of the plate, not the gun, so the part number stamped on the plate you fit is the answer. Glock describes the arrangement on its own G35 Gen4 MOS page as letting you “mount a reflex sight on the pistol’s slide without the need for a new slide or separate mounting system” (us.glock.com). Walther’s plates are explicit in the product name, for instance the Gen 2 plate sold as the ACRO footprint plate (waltherarms.com).
3. If it is milled, use size class, not lug count. Count sockets to land in a group, then split the group by body length: roughly 40mm of optic body for RMSc against roughly 46mm for DeltaPoint Pro, a split documented in OpticsPlanet’s footprint guide (opticsplanet.com). Docter sits in the same group and this dataset publishes no socket spacing for it, so a Docter-group optic has to be matched off the optic maker’s spec page. In the 2-lug group, RMR against Holosun K is a size question too: K optics are micro bodies for subcompact slides.
4. Count the sockets on the slide, not the pins on the plate. A mount presenting a 4-socket pattern frequently carries only 2 pins. The Optics Trade teardown of the DeltaPoint Pro standard puts it directly: “there are 4 sockets (recesses) in the mounting standard of the DPP” even where a mount uses two (optics-trade.eu). Reading pin count as socket count is how people buy the wrong optic.
5. Expect a factory document to be vague, and prefer the plate kit listing. HK’s own two pages disagree on how many plates exist for the VP9 cut: the Match page says five and the VP9A1 X Tactical page says “one of nine available adapter plates” (hk-usa.com). Neither names a footprint. When the maker’s pistol page will not say, the plate catalogue for that pistol will.

What to buy, in order

The data supports a short decision order and not much more. There are no prices anywhere in this dataset, so nothing below is a value judgement.

If you already have the pistol, the footprint question is settled and no ranking applies. Read the pattern off the pistol’s own page here and buy on it. On a plate system, the plate is the decision and the optic follows.

If you are buying the optic first and will keep it across pistols, buy RMSc: 186 of 196, the only pattern milled into slides in quantity, a plate on 14 of the 15 systems, and 12 of the 16 brands building one. What it will not get you is a Taurus TORO or an RMR-only Glock-pattern slide.

If you want one optic that covers everything, that does not exist, and the honest version is a pair. One RMSc optic plus one RMR optic covers all 196 pistols here, and no other pair of patterns does. If you would rather buy one optic and one plate, RMR is the pattern to hold, because all 15 plate systems sell an RMR plate and only 14 sell RMSc.

If you are buying the pistol with optics in mind, buy the plate pocket, not the milled cut. The median plate-system pistol reaches 84 optic pages and the median milled slide reaches 30. The best milled slide here is the Ruger RXM at 78, which beats no plate system except the Taurus TORO at 55. Count plates while you are at it: the five-plate systems reach 85 to 90, the four-plate systems 83 to 84.

If you need an enclosed emitter, check that first and let it override the rest. Only 27 of the 100 pages are enclosed and the preferred pattern changes: ACRO is 5 of 5 enclosed but reaches only 80 pistols and needs a plate on every one, RMSc gives 8 enclosed options across 186 pistols, RMR gives 3.

Full optic lists live on the hub pages, and the index of all 24 footprints and plate systems is at /footprints/.

What this dataset does not tell you

Four limits, stated because they bound every number above.

Length is not recorded per slide. The RMSc record on this site carries an explicit warning that the same screw and socket pattern exists at two physical sizes, roughly 40mm and roughly 46mm, and that a slide cut for the shorter will not take the longer. This dataset records which pattern each slide accepts but not which length it was cut for. So the 186 figure is a pattern match, not a guarantee that a specific 46mm optic clears a specific subcompact slide. Shield Sights, which defines the pattern, states on its own page that “The Shield footprint, used by the RMSc, is now the universal standard for many optic-ready subcompact handguns” (shieldsights.com), and that page names the pattern and its reach without publishing the screw spacing or the length split.

No page publishes a window dimension. All 100 optic pages here carry a null window width and height, so none of the comparisons above can be made on glass size, and “will this optic look right on that slide” is outside what this data answers.

Provenance is uneven. 48 of the 100 optic pages are flagged verified, 43 rest on a single source URL, and 3 fit no pistol at all. Per pattern that is RMSc 19 of 30 and RMR 14 of 33, so the two patterns recommended here are also the two best-evidenced, without either being complete.

Some plate rows are probably undercounts. Holosun K at one plate path is the clearest case: four plate systems here were built from fitment pages whose recorded wording lists a “407k / 507k” plate, and this dataset records those two optics as Holosun K while recording none of those four plate rows as presenting it. Resolving that would raise Holosun K’s reach above 27 and leave RMSc’s 186 untouched. Two pairs of pistol records also look like one gun recorded twice, the SIG P365 XL pair and the Ruger 5.7 pair, so treat any single row as a lead rather than a verdict.

Sources

Pattern geometry, reach and SKU counts: the published export bundle, version 2026-09-30, recomputed for this article. Product and specification claims, each cited in the text above: shieldsights.com on the RMSc pattern, ruger.com on the RXM’s three cuts, shadowsystemscorp.com on the MR920’s optic mounting, steiner-optics.com on the MPS-C footprint, holosun.com on the EPS-CORE, hk-usa.com VP9 Match and VP9A1 X Tactical on plate-mounted optic cuts, fnamerica.com on the Low-Profile Optics Mounting System, us.glock.com on the MOS concept, waltherarms.com on the Gen 2 ACRO plate, taurususa.com on the four TORO plates, optics-trade.eu on DeltaPoint Pro sockets, and opticsplanet.com on the 40mm against 46mm RMSc length split.

Related reading on this site: the RMSc footprint guide, RMSc against RMR, whether your pistol needs a plate, and the Ruger RXM’s optic compatibility.