Red Dot Footprints Explained: RMR, RMSc, DeltaPoint Pro, ACRO and the Rest

A footprint is the pattern of screw holes and recoil-boss recesses on the bottom of a pistol optic. If the optic's footprint matches the pocket in the slide, it bolts straight on. If it does not, you need an adapter plate or a different optic. The industry has settled on a few patterns, and knowing them saves you from buying a slide that will never take the dot you want.

The RMR footprint

Trijicon's RMR set the pattern for full-size pistol optics, and it is by far the most common cut. Two screws front and back, two recoil bosses at the rear, and a base a little over an inch wide. Optics from Holosun, Sig, Swampfox, Vortex and many others use the RMR pattern or a variant of it, and the majority of aftermarket cut slides are milled to it. If you own a full-size or compact double-stack pistol and have no strong opinion, an RMR-footprint slide keeps your options open.

Some makers use the RMR screw spacing but change the boss shape or add a locating pin, so an RMR-pattern optic may need small trimming or a different plate on a slide cut for a specific brand. Check the maker's fitment page before you order.

The RMSc footprint

Shield's RMSc pattern is the slim equivalent, sized for single-stack and micro-compact slides where the RMR would hang over the edges. Holosun's K-series, the Sig Romeo Zero, Swampfox Sentinel and the small Trijicon RMRcc all use it or something close to it. Micro pistols cut for the RMSc footprint are the fastest-growing part of the optics market because most carry guns now leave the factory cut this way.

A caution: the RMSc uses smaller screws and shallower bosses than the RMR, and a few makers offer a variant with different boss spacing. Confirm the exact footprint the slide is cut for, not just the family.

DeltaPoint Pro and the Sig variants

Leupold's DeltaPoint Pro pattern is wider, with its own boss layout, and it is the footprint behind Sig's Romeo1 Pro and the pocket on many Sig optics-ready slides. It is a good pattern, but far fewer aftermarket slides are cut for it, so plan on a plate if you want a DeltaPoint on a Glock-pattern slide.

ACRO and enclosed emitters

Aimpoint's ACRO has a fully enclosed emitter and its own mounting pattern with a clamp rather than screws through the body. Enclosed optics keep rain and lint off the emitter and have become popular on duty pistols. Several makers now offer enclosed optics that sit on an RMR footprint instead, which is the easier route if your slide is already cut to RMR.

Holosun's K and 407/507 families

Holosun deserves its own note because it sells more pistol dots than anyone else at the moment and its footprints are not all the same. The 407C, 507C and 508T sit on the RMR pattern. The 407K and 507K sit on Holosun's K footprint, which is RMSc-like but not identical: the screw spacing matches but the boss recesses differ, so a K-series optic on a true RMSc cut may need the bosses trimmed or a K-specific plate. The EPS and EPS Carry enclosed models follow the same split, RMR-compatible for the full-size and K-pattern for the carry version. When a slide is listed as cut for Holosun K, it means the K pattern and not the Shield pattern; when it is listed as RMSc, ask whether K-series optics have been test-fitted.

Docter, Noblex and the older patterns

The Docter pattern predates all of these and still appears on some European optics and on older adapter plates. It is worth recognising so you do not buy a bargain optic that fits nothing you own.

Plates and what they cost you

An adapter plate converts one footprint to another. It is how a factory modular-cut pistol takes any optic, and it is how a slide milled for RMR can take a DeltaPoint. Every plate adds height, one more interface that can shift under recoil, and another set of screws with their own torque figure. Good plates are steel or aluminium, machined rather than cast, and designed so the optic's bosses seat in the plate and the plate's bosses seat in the slide. Cheap plates that rely on screws alone are where optics come loose.

Picking a footprint

Full-size or compact double-stack: RMR. Most optics, most slides, most plates.
Slim micro-compact carry pistol: RMSc. Check the exact variant.
You already own a DeltaPoint Pro or a Sig Romeo1 Pro: look for a native cut or plan on a plate.
You want an enclosed emitter: consider an RMR-footprint enclosed optic before committing to a proprietary pattern.

Then choose the slide to match. The milling guide covers what a good pocket needs, and the fitting guide covers putting the slide on the frame. Pistols listed as optics-ready in the catalogue show the footprint or plate system in their details where the maker publishes it.

Height over bore and what it does to your zero

Every footprint choice also sets how high the dot sits above the barrel. A direct-milled RMR sits lowest; the same optic on a plate sits two to three millimetres higher; an enclosed emitter on a plate sits higher still. Height over bore changes the offset between where the dot is and where the bullet strikes at close range, and it decides whether your iron sights can be seen through the window. A quarter inch of extra height means about a quarter inch of low impact at contact distance and a slightly different zero at ten yards versus twenty-five. None of it matters much on a range gun; on a carry pistol you will want to know your offset at three yards and pick suppressor-height irons that show in the lower third of the window.

Screws, again

Every footprint has its own screw size and pocket depth. The optic's screws suit its own base on a plate; a direct-milled pocket usually needs a different length. Buy the screws the slide maker recommends, use thread locker, torque to specification, and mark the heads. Most optic problems are screw problems.

General information, not legal advice. Current as of September 2026. Laws change; check the official source before you act.