Guide to Pistol Red Dot Footprints
Posted by Monstrum on Aug 19th 2026
Must Know Before Buying!
A pistol red dot sight can greatly improve your speed and accuracy when shooting a handgun, but in order to mount one directly to your pistol’s slide, you must first ensure that your red dot sight has a compatible mounting footprint to your pistol’s slide. In this article, we’ll explain what mounting footprints are, describe some of the most common footprints today, and list a few of the more popular red dot sights that use each.
What is a Pistol Red Dot Mounting Footprint?
A pistol red dot mounting footprint is the layout of screw holes and sockets on an optic that correspond to pins on a pistol’s slide for direct mounting. Direct mounting on most modern handguns involves attaching an optic via two screws and usually two or four pins that act as recoil lugs on the slide that mate with recesses on the bottom of the optic. The layout of these screws and sockets vary by optic manufacturers, but most pistol red dot sights made today fall within six footprints: RMR, Shield RMSc, Holosun K, Delta Point Pro, Docter, and Acro. We’ll explain the differences between each in the following sections.
Optics Mounting Adapter Plates
While most “optics ready” pistol slides are milled for one specific mounting footprint, one more popular method for getting around mismatched patterns are optics adapter plates. Adapter plates are thin pieces of metal or plastic that sit between the pistol red dot sight and the pistol slide. They can be used to mount an optic of one pattern onto a slide with another.
While adapter plates are useful for mounting pistol optics to guns that wouldn’t otherwise be able to accept them, they come at the cost of added complexity and deck height. Most pistol red dot sights occlude the sight picture of factory iron sights, so suppressor-height sights are recommended in most cases if you want to be able to co-witness through your red dot.
RMR Mounting Footprint
One of the first modern pistol red dot sights to see widespread military adoption was the Trijicon RMR, and the pattern of screw holes that this pistol red dot used is called the RMR footprint. The RMR footprint consists of two screw holes apart and two recoil lugs in the front corners. This pattern is one of the most popular optic mounting footprints for full-sized and compact handguns.
Some red dot sights that use the RMR footprint include:
Trijicon RMR
Trijicon SRO
Holosun 507C X2
Holosun 407C X2
Swampfox Kingslayer
Swampfox Justice II
Monstrum Nitro+
Monstrum B.O.P.
Shield RMSc Mounting Footprint
The Shield RMSc pattern is the most popular mounting footprint among smaller sub-compact and micro compact pistols. It was developed by Shield Sights in 2018 and uses two screw holes and four pins.
Popular optics that use this footprint include:
Vortex Defender CCW
Swampfox Sentinel II
Sig Sauer Romeo Zero
Monstrum Nitro and Nitro+
Holosun K Mounting Footprint
The Holosun K is derived from the Shield RMSc pattern. This footprint has two screw holes and two pins at the front corners, though both of these fall in the same position as they do with Shield RMSc. The only differences are that the Holosun K footprint lacks the two rear pins and the front two are cut shorter than they are on the RMSc pattern. This means optics made for the RMSc pattern can mount to the Holosun K footprint, but optics with the Holosun K footprint can’t mount to RMSc pattern slides.
Popular optics that use this pattern include:
Holosun 407K X2
Holosun 507K
Holosun EPS
Holosun EPS Carry
Delta Point Pro Mounting Footprint
The Delta Point Pro footprint was created by Leupold for their larger full-size pistol red dot sights. This pattern has two screws and four pins similar to the RMSc footprint, but scaled up for larger optics.
Popular optics that use the Delta Point Pro footprint include:
Leupold Delta Point Pro
Bushnell RXS-100
Bushnell RXS-250
Eotech EFLX
Holosun SCS 320
Primary Arms GLX RS-15
Sig Romeo-X PRO
Vortex Defender ST
Vortex Defender XL
Vortex Venom Enclosed Micro Red Dot
Docter/Noblex Footprint
The Docter or Noblex mounting footprint consists of two screws and four pins. It is known by both names because it was originally invented by a brand called Docter which has since been acquired by Noblex as of 2017.
Optics that use this footprint include:
Noblex NV Sight II
Burris Fastfire 3
Leapers UTG OP3 Micro
Vector Optics Frenzy X
Vector Optics Frenzy FU
Vortex Venom
Aimpoint Acro
Last, but not least, we have the Aimpoint Acro footprint, which consists not of screws like the other footprints mentioned, but rather a perpendicular recoil lug and two grooves that clamp to corresponding edges on either side similar to picatinny rail.
Optics that use this footprint include:
Aimpoint Acro C-1
Aimpoint Acro C-2
Aimpoint Acro P-1
Aimpoint Acro P-2
Steiner MPS
Vector Optics Frenzy Plus
One Off Pistol Red Dot Mounting Systems
As pistol optics evolve, so too do the methods for mounting them. Pistol manufacturers are innovating several new ways of mounting pistol red dots that are not as widely available or popular as the footprints we’ve already covered, but we’ll mention them here.
Glock MOS (Modular Optic System)
The Glock MOS (Modular Optic System) is a mounting pattern made for Glock pistols that is meant to be used with separately sold plates that can fit any of the popular footprints, but also directly mount a few optics made specifically for the MOS pattern like the Holosun SCS. There are two sizes of the MOS pattern; the standard MOS which is made for full size optics, and another for RMSc width optics called Slimline.
Other handguns that use a similar system of plates that mount to a single pattern of slide include the Walther PDP and PDP Pro and Smith & Wesson M&P 2.0 pistols.
Glock COA Mounting Footprints
The COA is a true one off pattern designed in tandem with Aimpoint . Rather than relying on screws, the COA uses an A-mount system of angled wedge surfaces that are clamped down by a redesigned iron sight. While this system is a true one off that no other optic manufacturers have adopted yet, its engineering solves one of the most common failure points for direct mounted pistol red dot sights: the screws. It solves this by relying on wedges which tighten under the force of recoil as opposed to screws which bear significant shearing force.The COA is an optic and gun combo that only works with the included Aimpoint optic.
Sig Sauer Sig LOC Mounting Footprint
The SIG-LOC and SIG-LOC PRO mounting footprints are unique to Sig Sauer optics. Both attach with two screws and have a single pin at the back, but also a forward facing lug designed to resist the upward shearing force of muzzle flip. This forward facing lug fits into a recess within the front edge of the optic cut on a slide. Thus far, only Sig Sauer pistols ship with this mounting footprint and they have a smaller version for their p-365 pistols.
Springfield Echelon Variable Interface System
To solve the issue of varying optic footprints, the Springfield Echelon was designed to incorporate 3 of the most common footprints on the slide directly from the factory. They achieve this with 3 sets of self-locking interchangeable pins and three pairs of screw holes. This allows the slide of the optic to be reconfigured into the RMR, Delta Point Pro, or Shield RMSc patterns for direct mounting simply by changing out a set of pins. The Echelon can also use the optics with the ACRO or Docter/Noblex patterns with an adapter plate.
Conclusion
Once you know what mounting footprint your pistol has, choosing a compatible red dot sight is as simple as verifying the footprint matches what your pistol slide has been cut for. If you want to switch to a non-compatible optic, an adapter plate can be a quick and easy way to do so if you don’t mind the extra height and screws.
For quick and easy reference, here’s a master chart for the mounting footprints we’ve covered along with some of the optics that use them:
| Footprint Name | Screw Holes | Pins / Lugs | Example Optics |
|---|---|---|---|
| RMR | 2 | 2 front pins | Trijicon RMR/SRO, Holosun 507C, Monstrum Nitro+/B.O.P. |
| Shield RMSc | 2 | 4 pins | SIG Romeo Zero, Swampfox Sentinel II, Vortex Defender CCW, Monstrum Nitro/Nitro+ |
| Holosun K | 2 | 2 front pins | Holosun 407K/507K/EPS Carry |
| Delta Point Pro | 2 | 4 pins | Leupold Delta Point Pro, EO Tech EFLX, Vortex Defender XL/ST |
| Docter/Noblex | 2 | 4 pins | Burris Fastfire 3, Noblex NV Sight, Vortex Venom (Open Emitter) |
| Aimpoint Acro | Clamp System | 1 center lug, 2 side grooves | Aimpoint Acro P-2, Steiner MPS |