The RMSc footprint

How to identify an RMSc cut without a caliper

Work the slide, not the box. Look straight down into the milled recess with the cover plate off and count three things in this order.

1. Screw holes: two. They sit at opposite corners of the recess on the long axis, and the optic screws pass down through its body into the slide. That is a screw-through mount. If the optic instead clamps sideways onto a rail-like groove with a single cross bolt, you are looking at an ACRO cut, not this one. Compare on the ACRO hub.
2. Recoil bosses: four, at the corners. Two forward, two rear, standing proud of the floor of the cut. Four is the number that separates RMSc from the two patterns nearest to it. The Trijicon RMR pattern has two front lug sockets, not four. The Holosun K pattern keeps the two front lugs and deletes the two rear ones.
3. Length class. The recess is either about 40mm long or about 46mm long. Both lengths use the same two screws and four bosses, which is exactly why people buy the wrong optic. The 40mm class is the RMSc class: Shield RMSc, Sig RomeoZero, Holosun EPS Carry shell. The 46mm class is the DeltaPoint Pro class. If you cannot get a rule in there, read the slide marking or the manufacturer’s own spec page for that model before ordering.

On the optic side the tell is the underside. An RMSc footprint optic has two through holes and four shallow sockets in its base. The Shield RMSc is the reference part (shieldsights.com), and the Holosun EPS-CORE is the widely available enclosed equivalent (holosun.com).

Pattern and dimensions

What this dataset publishes for the RMSc footprint today:

Property	Value	Source
Mounting style	Screw-through	dataset
Mounting screws	2	dataset
Recoil bosses	4, corner positions (2 front, 2 rear)	dataset
Footprint family	Shield RMS	dataset
Body length classes	Two, about 40mm and about 46mm, sharing one screw and boss layout	dataset
Optics recorded on this pattern	30 pages covering 33 SKUs from 12 brands	dataset

Screw thread size, screw centre spacing and boss diameter are not published here. No manufacturer drawing carrying those figures has been read into the dataset yet, and the rule on this site is to print a null rather than a guess. When a drawing is sourced, the numbers land in this table with the drawing linked next to them. Until then, buy the screws that ship with your optic, or the length the optic maker specifies for your slide, and do not infer a thread pitch from a forum post.

One tolerance note worth stating because it explains a real fitment complaint: the recoil posts on a Shield RMS body run about 0.4mm undersized against the DeltaPoint Pro sockets, so an RMS on a DeltaPoint Pro cut can sit loose even though it bolts down flat. See the DeltaPoint Pro hub and Leupold’s own product page (leupold.com) before mixing those two.

Look-alikes that will not interchange

RMSc against RMS. Same screws, same four bosses, different length. RMS is the 46mm part (shieldsights.com), RMSc the 40mm part. Shield also sells the even shorter RMSsc (shieldsights.com). Read the length before the acronym.

RMSc against Holosun K. The K pattern is a deliberate modification of this one: identical screw spacing, identical front lug positions, rear lugs removed so the body can be sealed. That is why a 507K or an EPS Carry is not simply an RMSc optic (holosun.com). This dataset keeps them apart: 30 optics on RMSc, 5 on Holosun K, with 26 pistols cut for K directly.

RMSc against RMR. Different family entirely. Two lug sockets rather than four, and a larger body. The RMR hub carries 33 optics against 30 here, but only 7 pistols in this dataset are cut for RMR directly against 80 for RMSc. RMR wins on optic choice, RMSc wins on slides. The side-by-side is in RMSc vs RMR.

RMSc against DeltaPoint Pro. The dangerous pair, because the screw and boss layout really is the same and only the length differs. Covered above.

The Glock 43X MOS and 48 MOS. Named MOS, cut RMSc. They take an RMSc optic straight onto the slide with no plate, unlike every full size Glock MOS pistol. Two of the 80 direct-fit pistols on this page are these Glocks.

How a plate gets you to RMSc

106 pistols that are not cut for RMSc still take an RMSc optic, through 14 different plate paths. That is the second half of this footprint’s reach: 186 of the 196 pistols in the dataset, or 94.9 percent, can carry an RMSc optic one way or the other. No other footprint here comes close.

In words, a plate path works like this. The slide is milled for a proprietary interface that is not a footprint at all. A plate drops into that interface and its top face carries a real footprint. Buy the plate that presents RMSc and the slide behaves, for optic-buying purposes, like an RMSc slide. The plate table for each system lives on that system’s own hub, not here.

The four largest paths to RMSc, by pistol count:

• SIG P320 X-series, 16 pistols. An aftermarket modular adapter presents RMSc on the X-series cut (outerimpact.com).
• Glock MOS, 16 pistols. An RMSc/Shield MOS adapter plate (opticsplanet.com).
• S&W M&P CORE, 14 pistols. A CORE plate presenting RMSc (chpws.com).
• FN 509, 12 pistols. The Low-Profile Optics Mounting System with an RMSc plate (chpws.com).

Ten more systems present RMSc on smaller pistol sets, including Beretta APX A1 (beretta.com), Canik METE (outerimpact.com), CZ P-10 OR and HK VP9 OR (chpws.com), Walther PDP 2.0 (optics-spot.com), Springfield Echelon VIS, Springfield XD OSP (springfield-armory.com) and Springfield AOS (springfield-armory.com). Every path and its pistol list is in the plate section further down this page.

A plate costs you height above the bore and one more interface that can loosen. If your slide is cut for RMSc directly, that is the better mount.

How to choose an RMSc optic

There are no prices on this page and no rankings the data can support. What the data does support:

• Supply is not your problem. 30 optic pages covering 33 SKUs from 12 brands fit this footprint, from budget to premium: Shield Sights, Sig Sauer, Meprolight, Riton, Bushnell, Primary Arms, Swampfox, Vortex, Burris, Crimson Trace and Holosun.
• Decide open or enclosed first. An open emitter is lighter and shorter. An enclosed emitter keeps lint and rain off the emitter, which matters for a pocket or appendix carry gun. Both exist on this footprint, for example the enclosed Holosun EPS-CORE and Primary Arms CLx (primaryarms.com) against the open Vortex Defender-CCW (opticsforce.com).
• Confirm the length class for your specific slide. This is the step people skip. The screws will thread either way; the optic will overhang or the cut will show.
• Check the optic page, not the brand. Each optic page on this site lists the pistols it fits and links the source for that claim.

Nothing here is verified against a physical sample. 41 of the 100 optic pages in this dataset now carry a verified flag, which means the maker’s own page (or two independent retailer pages) was read and the sentence stating the footprint is recorded against the record. The other 59 are sourced but not yet re-read, and single-source records are common. Treat the fit claims as sourced research, then confirm against your own slide before you spend money.

Where to go next

• The full chart: all optic footprints and plate systems.
• The long form article this hub owns: RMSc footprint guide.
• When your slide is not cut for what you want: do you need an adapter plate?
• The largest single RMSc pistol family in the dataset: Sig P365 red dot compatibility.
• Popular RMSc slides: Sig P365XL, Springfield Hellcat OSP, Ruger RXM, S&W M&P Shield Plus OR, Taurus GX4 TORO.