Docter Footprint vs RMR: 6 Optics, 55 Pistols

Every single pistol in this dataset that can mount a Docter optic can also mount an RMR optic. Not most of them, all 55 of them. The Docter footprint reaches 55 of the 196 optic ready pistols here and the RMR footprint reaches 117, and the 55 are a strict subset of the 117 with no exceptions in either direction. Choosing Docter over RMR never buys you a pistol. It only costs you optics: 6 pages on the Docter pattern against 33 on the RMR.

That is the whole answer to “RMR or Docter”, and it is worth stating in that blunt form because the two patterns are usually compared as if they were rivals for the same slot. They are not. On this site, Docter is a pattern you end up on because of an optic you already own or a sight you specifically want, never because of the gun. If the gun is the constraint, the RMR pattern strictly dominates.

Every number below is recomputed from the published dataset bundle for this article, version 2026-09-23. The bundle holds 196 optic ready pistols, 100 optic pages covering 135 individual SKUs, and 24 footprint and plate system hubs. The Docter footprint hub owns the current optic list and the mount paths, and the RMR hub owns the RMR side. What follows is the shape of those numbers, which is the part no single hub can show you.

Six optics, four brands, one identical fit list

The Docter group is small and unusually uniform. Six optic pages, six SKUs, no product families collapsed behind any of them, from four brands:

Optic	Brand	Emitter	Pistols it fits	Verified here
FastFire 3	Burris	open	55	no
FastFire 4	Burris	open	55	yes
CTS-1250	Crimson Trace	open	55	yes
SLx RS-10	Primary Arms	open	55	yes
Venom	Vortex	open	55	no
Viper	Vortex	open	55	no

Two things in that table do real work.

The first is the emitter column. All six are open emitter designs. There is no enclosed Docter optic on this site at all, and that is not a sampling accident of a small group: across the whole 100 page catalogue, 27 pages are enclosed, and they land on RMSc (8 of 30), DPP (5 of 15), RMR (3 of 33), ACRO (5 of 5), Holosun K (3 of 5), Holosun 509T (2) and Holosun EPS (1). Docter gets zero. If you have decided you want a sealed emitter window for carry or for weather, the Docter pattern is not a shortlist you should be building, and no plate will change that.

The second is that the fit count is identical down the column. Not close, the same number six times. That happens because none of these optics reaches a pistol on its own merits: every fit is a plate fit through the same ten plate paths, so the six optics inherit one shared reach. It also gives you a quick diagnostic when reading a pistol page on this site. If you see a group of six optics you cannot place, check whether the number next to them is 55.

Here is where Docter sits among the nine true footprints in the bundle, as opposed to the 15 factory plate systems, which are a different kind of object:

Footprint	Optic pages	SKUs	Brands	Screws and lugs	Slides cut for it	Reached by plate	Total reach
RMSc	30	33	12	2 screws, 4 lugs	80	106	186
RMR	33	47	7	2 screws, 2 lugs	7	110	117
DPP	15	16	5	2 screws, 4 lugs	2	110	112
ACRO	5	5	3	clamp, 1 stopper	0	80	80
Docter	6	6	4	2 screws, 4 lugs	0	55	55
C-More STS	1	1	1	2 screws, 0 lugs	0	28	28
Holosun K	5	8	1	2 screws, 2 lugs	26	1	27
Holosun 509T	2	8	1	clamp, 1 stopper	0	0	0
Holosun EPS	1	9	1	2 screws, 4 lugs	0	0	0

Docter is fifth by reach and fourth by optic count. The SKU column is where the gap with RMR really opens: 6 SKUs against 47. That RMR total is not Trijicon’s doing, which surprises people. Trijicon holds 4 of the 33 RMR pages and 8 of the 47 SKUs. Holosun holds 16 pages and 26 SKUs, more than half the pattern’s SKU count on its own, because the 507C and 407C lines and their variants all land here. The RMR pattern is large because other brands adopted it, and that is exactly the mechanism Docter has not had: its 6 pages come from 4 brands and not one of them contributes more than two.

One more relationship is worth naming before moving on, because it is the tidiest structure in the whole bundle. The C-More STS pattern reaches 28 pistols, and those 28 are a strict subset of Docter’s 55, which are in turn a strict subset of RMR’s 117. Three patterns, nested exactly, no crossovers. Any pistol that can take a C-More STS optic can take a Docter optic, and any pistol that can take a Docter optic can take an RMR optic.

Two screws and four sockets: the RMR tell

If you are holding a plate or an optic and trying to decide which pattern it is, the useful distinction between RMR and Docter is not on top. Both are what this dataset calls screw through patterns: two screws pass down through the optic body into the slide or the plate beneath it. Two holes, roughly the same spacing to the naked eye. That is why the two get confused in the first place.

Turn the optic over. The RMR pattern records two recoil lugs: raised bosses on the mounting surface that the optic’s underside pockets drop onto, positioned fore and aft. The Docter pattern records four, and they are a different shape. OpticsPlanet’s guide to the most common red dot footprints describes the Docter pattern as one that utilizes 2 screw holes and 4 sockets to accept recoil pins, and that is the wording that matters: sockets in the optic, pins on the mount, arranged at the corners of the rectangle the two screws bisect. Optics Trade’s survey of footprints on red dot sights covers the same family under the Docter and Noblex names.

Here is the honest limit of the count as a test. Counting sockets separates Docter from RMR cleanly, because two is not four. It does not separate Docter from RMSc or from DeltaPoint Pro, because both of those also record two screws and four sockets in this dataset. What separates those three is overall size and screw spacing, not the socket count, and none of the three is a subset of another: a DPP optic will not drop into a Docter pocket. So the socket count answers “is this an RMR pattern” and nothing more. For the rest, the plate marking or part number is the only reliable reading, which is why the next section matters more than the geometry does.

In practice the plate is where you should look first, because on this site there is no such thing as a Docter cut slide. Zero of the 196 pistols here have a factory milled Docter pocket. Every Docter fit in the bundle is a plate sitting between the optic and the slide, and plates arrive marked. Beretta’s 90-Series red dot optic plate kit listing records a plate described for a Burris or Docter pattern red dot alongside its ACRO, Leupold and Trijicon plates, and Springfield’s Echelon Variable Interface System pin set page sits alongside a plate the company sells explicitly for ACRO and Docter footprints. When a kit names the pattern on the box, that beats anything you can measure with a ruler.

The name trap: Venom, FastFire, RS-10

The most expensive mistake on this pattern is not misreading geometry. It is buying by family name. Four brands carry Docter optics here and three of the four also sell a near namesake on a different pattern.

Vortex is the worst of them, and the trap is inside a single model name. The Venom is an open emitter sight on the Docter pattern, reaching 55 pistols. The Venom Enclosed is a DeltaPoint Pro pattern optic reaching 112, and its listing at DNW Outdoors is titled for DeltaPoint Pro footprint compatibility. Same family name, different pocket, roughly double the reach. Vortex holds 8 optic pages in this catalogue spread across three patterns: Venom and Viper on Docter, Defender CCW and Defender CCW Enclosed Solar on RMSc, Defender ST, Defender ST Enclosed Solar and Venom Enclosed on DPP. Knowing that a sight is a Vortex tells you nothing at all about what plate to order. EGW’s note on the Venom’s old and new footprints and its Viper and Venom mount listing are the first sources behind both Vortex rows here, and both are third party rather than Vortex’s own pages. On 2026-10-04 each row cleared the bar on a second independent source instead: Taurus’s own TORO plate kit listing groups the Venom with this pattern on one plate, and OuterImpact’s Canik mount page lists both the Venom and the Viper under its Docter plate. Vortex still publishes nothing here that names the pattern.

Burris splits four pages across three patterns. The FastFire 3 and FastFire 4 are Docter at 55 pistols; the FastFire C is RMSc at 186, the widest reach of any optic on the site; the FastFire E is ACRO at 80. The letter is the whole message. Burris’s own FastFire 4 page gives its mounting line as Picatinny Mount and Docter Optic, which is the manufacturer statement that lets this dataset flag that row verified; the FastFire 3 page does not name the pattern in the same way, so its sibling row still rests on a third party compatibility article and stays unverified.

Primary Arms hides its split behind one trailing letter. The SLx RS-10 is Docter, and the company’s product page says it fits the commonly used Docter/Noblex footprint. The SLx RS-10R is RMR, and its product page says it pairs the same sight with the Holosun 507c footprint. One character in the SKU, 55 pistols against 117.

Crimson Trace is the mildest case but the same shape. The CTS-1250 is Docter, and Crimson Trace’s product page lists its footprint as Docter compatible. The CTS-1550 is RMSc at 186 pistols. Three hundred in the model number is not the same pattern as fifteen fifty.

Ten plate systems carry a Docter plate, five do not

Of the 15 factory plate systems in this dataset, 10 have a plate recorded that presents Docter and 5 do not. Those 10 paths account for all 55 reachable pistols, with no pistol on two paths, because a pistol belongs to exactly one plate system. Each system’s own hub owns its full pistol list and its plate table; the column that is new here is the last one, which is the number that actually decides anything.

Plate system	Pistols	Optics that pistol can reach	Docter’s share
SIG P320 X-series	16	85	7.1%
Beretta APX A1 / 90-Series	10	89	6.7%
Walther PDP 2.0	10	90	6.7%
Canik METE / TP9	7	85	7.1%
Springfield Echelon VIS	4	89	6.7%
Taurus TORO	4	55	10.9%
Ruger factory plate	1	85	7.1%
Springfield AOS	1	84	7.1%
Springfield XD OSP	1	89	6.7%
Walther PDP 1.0	1	89	6.7%

The five systems with no Docter plate recorded are S&W M&P CORE, FN 509, CZ P-10 OR, HK VP9 OR and Glock MOS. Those five share an interesting property: their recorded plate sets are identical, each presenting exactly ACRO, DPP, RMR and RMSc. They are the four pattern systems, and Docter is the pattern that four pattern kits leave out.

The provenance for the ten that do carry it is mostly plate listings rather than pattern documentation, and it is worth knowing which is which. Four of the paths come from a modular adapter product line whose own optic list names the pattern directly alongside the Vortex Viper, Vortex Venom and Burris FastFire 2, 3 and 4: the SIG P320 X5 adapter, the Canik METE adapter and the Ruger-57 adapter. Springfield contributes three paths from its own store: the AOS system’s plate page, the XD OSP optic mounting plate and the Echelon VIS pin set linked above. Taurus contributes the fourth pattern on its own kit page. Both Walther generations rest on a single third party plate guide, Optics Spot’s explainer on PDP optics ready plate versions, which is the thinnest evidence of the ten and is flagged as such on the records.

Taurus TORO: the one platform where Docter earns its place

On nine of those ten systems Docter is a rounding error: six or seven percent of what the pistol can already reach, and everything it offers is available in larger numbers on another pattern the same kit supports. On the tenth, the arithmetic flips.

The four Taurus TORO pistols here reach 55 optics each, the lowest total of any Docter capable pistol in the bundle and 61.8% of what a Walther PDP Gen 2 reaches. Take a Taurus G3c TORO and decompose that 55: RMR contributes 33, DPP contributes 15, Docter contributes 6 and C-More STS contributes 1. There is no RMSc row, because the TORO kit records no RMSc plate. That makes the TORO the only Docter carrying system in the dataset that is not also an RMSc system, and it means the four TORO pistols, the three G3 variants and the TX22 Competition, are the only four pistols on this site that can mount a Docter optic but not an RMSc one.

Docter is 10.9% of a TORO owner’s options against roughly 7% everywhere else. In absolute terms it is the same six sights, but as a share of a short list it is the difference between an afterthought and a real branch. It also means the TORO’s practical enclosed emitter count is 8 rather than the 21 a Beretta or Walther owner gets, and none of those 8 are Docter, so the shortening bites in both directions.

Compare that to the arithmetic on a wider platform. A SIG P320 XCompact reaches 85: RMR 33, RMSc 30, DPP 15, Docter 6, C-More STS 1. A Beretta 92XI reaches 89: RMR 33, RMSc 30, DPP 15, Docter 6, ACRO 5. A Walther PDP Gen 2 optic cut reaches 90, which is that same 89 plus one direct fit optic on the PDP 2.0 cut itself. A Springfield XD-M Elite OSP reaches 89 with a different tail: RMR 33, RMSc 30, DPP 15, Docter 6 and Holosun K 5. In each of those the Docter six is the smallest non trivial group on the list.

The 141 pistols with no Docter path

The other side of 55 is 141, and those 141 split into two unequal groups that call for completely different answers.

102 of them have a milled slide. These are the pistols whose slides are cut for a footprint directly, overwhelmingly the 80 cut for RMSc. A milled slide has no plate to swap, so there is no Docter plate to buy and no adapter path to argue about. If you own a pistol with a factory RMSc pocket and you have a FastFire 3 in a drawer, this dataset has no fit for you, and the honest version of that sentence is that the answer is a different optic, not a different plate.

39 of them are on a plate system that has no Docter plate recorded. That is 14 S&W M&P CORE pistols, 12 FN 509s, 7 CZ P-10 OR models and 6 HK VP9 OR models. These are the frustrating ones, because the hardware question is open rather than closed: the pistol has a plate pocket, the kit just does not contain a Docter plate in any listing recorded here. The 16 Glock MOS pistols sit in the same position, though they land in the milled count above because of the one direct fit optic recorded on the MOS cut.

That Glock MOS gap is the loudest unresolved question on this pattern, and it deserves stating plainly rather than burying. Primary Arms’ own SLx RS-10 page, cited above, says the sight fits the Docter/Noblex footprint and that an adapter plate for Glock MOS is included in the box. This dataset records no Docter plate path on the Glock MOS system. Both of those statements cannot describe the same world. The likeliest reading is that the MOS plate kit contains a plate that presents Docter and that no listing recorded here names it, which would mean the Docter reach is understated by 16 pistols. Until a Glock or plate maker page naming that plate is recorded, this site will not claim the fit, because a fit nobody published is a fit this dataset does not have.

Choosing between a Docter optic and an RMR optic

If the pistol is already chosen and you are shopping for glass, the decision is not close, and the subset relationship is the reason. Every Docter capable pistol is RMR capable, so picking the RMR pattern costs you nothing in compatibility and gains you 27 additional optic pages, 51 additional SKUs and 3 more brands. On a pistol whose kit carries both plates, the RMR plate is the one with the larger future: more current models, more price points, more enclosed options if you change your mind later.

Three situations invert that, and they are all situations where the optic came first.

You already own the sight. A FastFire 3 or an older open emitter Venom is a real object sitting in a drawer, and the cost of using it is one plate. Check that your pistol is one of the 55 and that its kit sells the Docter plate separately, then buy the plate rather than a new optic. This is the ordinary case and it is a perfectly good reason to mount a Docter sight.

You want a specific current model. The FastFire 4 is the only one of the six flagged verified against its own manufacturer’s statement of the pattern, the other four verified rows resting on a second independent source rather than on the optic maker, and it is a current product with a multi reticle option. Wanting that particular sight is a reason. Wanting “a Docter sight” in the abstract is not.

You own a Taurus TORO. As above, six of 55 is a different proposition from six of 89, and the TORO’s plate kit sells the plate, so the pattern is a live branch rather than a footnote.

Everywhere else, and particularly if you are still choosing the pistol, treat Docter as a legacy pattern that this dataset supports rather than one it recommends. The RMR footprint hub lists all 33 of its optics; the Docter hub lists all 6.

What this dataset does not know about Docter

Four gaps, stated so you can weigh them yourself.

One of the six rows is unverified. 48 of the 100 optic pages on this site carry a verified flag, which means either a manufacturer page quote naming the pattern for that exact model, or two independent sources saying so, has been recorded against the row. On Docter, the FastFire 4, the CTS-1250 and the SLx RS-10 clear that bar on the optic maker’s own page. The Venom and the Viper cleared it on 2026-10-04 on the second route, two independent plate listings each: Taurus’s own TORO plate kit for the Venom and OuterImpact’s Canik mount page for both. The FastFire 3 is the one that does not, because its Docter claim rests on a third party compatibility article and Burris’s own FastFire 3 page does not name the pattern the way the FastFire 4 page does. It is probably right and it is not proven here.

The pattern description names more optics than the catalogue carries. The Docter footprint record’s own description also names the Burris FastFire 2, the Hex Dragonfly, the original SIG Sauer Romeo1, the Meopta Meosight and the Viridian RFX25. None of those has a page in this dataset, so none of them appears in the 6, and their absence is a catalogue gap rather than a statement that they are not Docter. Expect the optic count to grow if those rows are ever added.

No manufacturer geometry citation exists for the pattern itself. The Docter record rests on two footprint reference articles, the OpticsPlanet guide and the Optics Trade survey linked above. Neither is Docter’s or Noblex’s own documentation. The screw spacing and socket dimensions are not published on this site because they are not recorded from a first party source, and stating a number we cannot cite would be worse than the gap.

The Walther plate evidence is thin and the Glock MOS question is open. Both Walther generations’ Docter paths come from one third party plate guide, and the Glock MOS discrepancy described above is unresolved. If the MOS plate turns out to present Docter, the reach figure in this article moves from 55 to 71 and every share percentage in the plate table moves with it.

None of that changes the headline. Docter is a real pattern with six real optics and 55 real pistol paths, and it is strictly contained inside a pattern with 33 optics and 117 pistol paths. That containment is the fact worth carrying out of this article.

Sources

• OpticsPlanet, a guide to the most common red dot footprints
• Optics Trade, footprints on red dot sights
• Burris FastFire 4 and FastFire 3
• Burris FastFire C and FastFire E
• Crimson Trace CTS-1250 and CTS-1550
• Primary Arms SLx RS-10 and SLx RS-10R
• Vortex Venom Enclosed listing, DNW Outdoors
• EGW, Vortex Venom new vs old footprint and EGW Viper and Venom mount
• Beretta 90-Series red dot optic plate kit
• Springfield Echelon VIS complete pin set, Springfield AOS and XD OSP optic mounting plate
• OuterImpact adapters: SIG P320 X5, Canik METE, Ruger-57
• Taurus TORO optic mounting plates and screws kit
• Optics Spot, Walther PDP optics ready plate versions explained