Not too many years ago, red dot sights on handguns were a novelty—previous generations of shooters had only known open/iron sights. When red dots started showing up on handguns, many felt they were not needed and only complicated the process. In some ways, the gun world is slow to accept new things, and adding an optic to a handgun was a big jump from the existing “norm.”
Mounting the Pistol Red Dot
As stubborn as we are, we slowly accept new methods and ideas. Today, mounting an optic on a handgun is all but expected. Manufacturers still launch new models that are not optics-ready, but they’re becoming far and few between. It only makes sense for modern handguns to be “optics-ready” anyway. If you don’t want to use an optic, no problem—but if you do, it’s nice to have that option. However, selecting the optic and making sure it is compatible with your gun can be a little confusing.
This is what brings us to red dot footprints.
Most of the time, when a new red dot sight comes out, it lists the footprint. This can be confusing because there are so many different footprints out there. If you use a wide variety of red dots regularly, this isn’t a complicated subject. But if not, you probably have to do a quick search to find out what footprint your handgun has.
That’s the point of this guide. Here’s the basic rundown on the most common standards for mounting red dots to handguns.
Glossary of Red Dot Mounting Terms
There are a lot of terms and abbreviations associated with red dots and how they mount to the gun. Each year, it seems more just keep popping up too. When searching for a red dot, it’s easy to focus on the brand, price, and overall size of the optic. But you also want to pay attention to the footprint of the optic to make sure it will work with your handgun.
The following are some common terms you will see regarding pistol-mounted red dots.
What is the Footprint?
The footprint of an optic is the physical interface between the bottom of the optic and the top of the firearm (or mounting plate). A footprint typically involves a pattern of pins and holes over a specific area made for an optic to mount to the gun. Screws and/or pins are used to secure the optic to the top of the gun, so the optic must match those hole patterns. We will talk more about these below.
This means an optics manufacturer must use a footprint on the bottom side of the optic that matches a specific footprint for a handgun. Firearms manufacturers must cut out an area on the slide for the red dot to connect to. This cut-out area, along with the hole placement for screws and pins, dictates what the “footprint” will be.
Both the cutout on the slide and the bottom of the optic must match. If they do not, it will not work unless an adaptor plate is used.
Each different footprint will have a name, which we will discuss more below.
Some footprints are more popular than others, so you will see them used often. For example, the term “RMR” is associated with many optics. RMR is a footprint mounting pattern made popular by Trijicon’s RMR red dot. But you can also find other optics, like the Holosun 507c, Primary Arms GLx, Swampfox Liberty II, and others that use the RMR footprint. During SHOT 2026, the RMR and Shield RMSc appeared to be two of the most popular footprints being used.
Adaptor Plates
An adaptor plate is basically a thin piece of metal made to connect an optic to a specific gun. In some cases, an adaptor plate will have a different footprint on each side. This would be needed if the gun and optic used different footprints.
What has become more common, however, is for a manufacturer to use their own modular system. This would be a specific pattern on their guns that only works with their adaptor plates. Most companies that do this offer multiple adaptor plates so you can attach the optic of your choice.
This provides the customer with more options for mounting a red dot. Instead of a handgun only working with, say, the RMR footprint, they provide adaptor plates made just for their gun. Each plate connects to the slide on the handgun using its own system, but has a standard footprint on the top of the plate. This is why you often see optics on handguns that have a thin metal plate between the optic and slide of the gun.
One example of this is Glock’s MOS mounting system. Glock has their own pattern of cuts and grooves made just for connecting their adaptor plates. It’s called the “MOS” system. But they provide multiple MOS adaptor plates with various footprints on the top. This means you can choose the plate with the footprint you need and then connect your red dot to the handgun.
Screw Hole Pattern
The footprint of an optic will have a specific pattern for screws and bolts that mount the optic to the gun or optic plate. When you screw the optic to the gun, the screws must line up with the holes in the slide.
Guns that use plate adaptors may have multiple holes on the tops of the slide. This is so the screws for a specific footprint can pass through the optic plate and into the top of the gun.
Note that some screw patterns can conflict, even in situations where compatibility is indicated (or that at least look that way). Shared sockets with misaligned threads are possible. For instance, there were reports (albeit many years ago) that while the corner socket positions of the Meprolight MicroRDS, Delta Optical MiniDot HD25 matched the Docter/Noblex standard (q.v.), their respective screw holes didn’t line up with standard Docter patterns.
Remember thread pitch! When you’re attaching an optic to a slide or adapter plate, lining up the hole spacing may not maintain a secure hold if the wrong thread pitch is used. Using an imperial screw in a metric plate (or vice versa) won’t just fail to seat properly — forcing a mismatched thread pitch will cross-thread and strip the hole on installation, before the gun is ever fired. Even if the footprint’s hole spacing matches up, always confirm thread pitch before installing.
Bolt Pattern
A bolt pattern for an optic is the location and number of bolts, also known as pins or recoil lugs. These bolts stick up from the top of the slide on the gun or optics plate.
An optic will have holes in it made to slide over these bolts (see photo above). Some footprints use four bolts, and others use two. The location and distance between the bolts will also be specific to each footprint.
In some cases, a manufacturer will place multiple screw holes and “pin” holes on their slide. This is done so multiple footprints will work on the slide. Simply place the pins in the correct pin holes and find the screw holes that line up for that optic.
Warning: Vertical hole alignment is only part of what makes optics and footprints compatible. Some guns (like custom direct-milled Glock slides and early PDPs) have a forward physical overhang that interferes with screw hole alignment. That overhang hits the slide before the holes line up appropriately, meaning that despite a matching footprint standard there is no compatibility.
The Multi-Footprint Evolution (Revolution?)
In recent years, higher-end (or maybe it’s better to say more advanced) optic-ready slides can provide simultaneous cross-compatibility with RMR, RMSc, and DeltaPoint Pro footprint standards without modifying or switching out base plates. They accomplish this with a modular layout of removable index pins that are positioned by the user. This doesn’t include all models, however, and is not a feature of all (or even a majority of) optic-ready slides. Enclosed emitter cross-bolt optics remain an exception. These RDS models (like the ACRO) still necessitate an adapter plate.
Still, it’s nice to have that alternative to multi-drilled plates, and the multi-footprint versions will almost certainly become increasingly common.
Common Footprints for Optics
Trying to figure out all the footprints used by optics and gun manufacturers is confusing. Here is a list of the most common footprints you will see associated with pistol-mounted red dots.
RMR Footprint
The RMR footprint has two screw holes and two front bolts (recoil lug holes on the optic) in the corners. This is one of the most popular footprints used with full-size pistol-mounted red dots. Here are a few of the red dot optics that work with the RMR footprint.
- Trijicon RMR, SRO
- Holosun 507C, 407X2 and many more
- Swampfox Kingslayer, Justice, and Liberty
- Riton X3 Tactix PRD
- C&H Precision Comp
- Eotech EFLX CE (fits both DPP and RMR)
RMRcc Footprint
Trijicon shrunk the RMR platform for the RMRcc, purpose-built for slim carry pistols. It drops the RMR’s front recoil-stop sockets entirely, using a proprietary two-screw hold instead — so despite the name, it is not interchangeable with a standard RMR cut. A slide milled for RMR will not accept an RMRcc without an adapter plate.
Optics using the RMRcc footprint:
- Trijicon RMRcc
- ADE NUWAcc PRO (RD3-021c PRO)
Shield RMSc Footprint
This pattern is often used on compact pistols with smaller handgun optics. It uses two screw holes and four recoil lugs. Here are some popular sights that use the RMSc footprint.
- Swampfox Sentinel II
- Vortex Defender
- Primary Arms Classic Series 21mm Micro Reflex Sight
- JP Enterprises Jpoint
- Sig Sauer Romeo Zero
- Holosun 507K, EPS Carry
DeltaPoint Pro Footprint (DPP)
Aside from the RMR and RMSc footprints, the DPP footprint, named after the Leupold DeltaPoint Pro optic, is extremely popular. It is similar to the RMSc footprint, but made for a larger optic, which requires a larger cut-out or “pocket” area for it to sit in.
The DPP pattern uses four small recoil lugs (instead of two larger ones like the RMR). These recoil lugs are located on each corner and fit into the corners of the optic. Two screw holes are located in front of the two rear recoil lugs to hold the optic in place.
Some of the popular optics that use this footprint include:
- Leupold DeltaPoint Pro
- Sig Sauer Romeo-X Pro
- Eotech EFLX CE (fits both DPP and RMR)
- Vortex Defender ST, Defender SL (open and enclosed emitter models)
Aimpoint ACRO Footprint
The Aimpoint ACRO footprint was built for enclosed-emitter optics — sealed designs that resist dust and debris better than open-emitter red dots. It uses a cross-bolt mounting system rather than the screw-and-lug pattern common to RMR/RMSc/DPP. Because the emitter housing is fully enclosed, ACRO-pattern optics tend to run longer than a standard RMR cut, so slide milling for ACRO often removes the rear iron sight dovetail.
Optics using the ACRO footprint:
- Aimpoint ACRO P-1 / P-2
- Steiner MPS
Glock MOS Footprint
Glock made their own proprietary system called the MOS (Modular Optic System). This system was made just for attaching their optics plates to their guns.
The plates connect to the slide using the MOS pattern, which allows an optic to mount on top of the plate. Each plate has a different footprint on top, allowing you to use optics with different footprints on their guns. The photo below shows some of Glock’s MOS adaptor plates and which footprints they work with.
For the most part, you will need an MOS adaptor plate to mount any optic on a Glock handgun. The Holosun SCS MOS works directly with the MOS footprint, meaning you can leave the adaptor plate off and mount the optic directly onto the Glock pistol. This system, however, was retired by Glock in 2026 with the release of their Gen 6 handguns.
Glock A-CUT Footprint — 2025
In 2025, Glock partnered with Aimpoint to create what they call the “A-CUT” mounting system, launched alongside Aimpoint’s purpose-built COA red dot. This system allows the front of the COA to slide under a lip on the slide of the gun, with two screws securing the optic on the back. In this configuration, rear sights help hold the optic in place while two screws go through the sights and into the slide.
The big advantage of this layout is a relief (on the mounting screws) from shear stresses. Usually the mounting screws of a pistol red dot are a point of failure. That’s due to the impact of recoil on an optic’s mounting system. The A-Cut’s geometry relieves a significant amount of that stress.
Because this system was exclusive to Aimpoint for one year, Glock handguns with the A-CUT system were sold as a combo package with the Aimpoint COA already mounted.
After the one-year period ended with Aimpoint, Glock announced in 2026 that it was expanding this partnership and working with other manufacturers to provide the A-CUT on their slide. These companies included Smith & Wesson, Sig Sauer, FN America, and Taurus.
Glock ORS Mounting System — New for 2026
When Glock announced its new line of Gen 6 pistols, it also announced it would be replacing the MOS system with a new one called ORS (Optics Ready System).
Instead of an MOS plate that screws onto the gun and then an optic to the plate, the ORS system lets you mount the optic directly to the gun. This is done by using “shim” plates instead of full adaptor plates. Three plate sizes work with most popular footprints on the market.
Another cool thing about the ORS system is that the cut-out area on the slide of the Glock pistol is deeper. This allows the optic to sit lower on the gun.
As you can see in the photo above, there are multiple holes in the slide of the gun for different footprints. The shim plate acts as a recoil buffer and provides recoil lugs for various optic footprints. The optic screws, however, go directly into the slide of the gun, making it more secure.
Docter/Noblex Footprint
Although it was probably the most popular footprint when optics were becoming a thing, the Docter footprint is falling in popularity. But some companies still use it today, so it’s on our list.
This footprint uses two screws and four posts. You will not see very many new optics using this footprint, but there are a few that work with the Doctor/Noblex footprint.
- Burris Fastfire 2
- Leapers UTG OP3 Micro
- Vortex Viper
- Vortex Venom
- Hawke Sport Optics
I’m guessing we will see less and less of this footprint over time. With new footprints being developed each year, some of the less-used footprints, like this one, will fade away.
Cautionary note: A few optics built on the Docter pattern ship with wider threaded sockets than the legacy Docter/Noblex specification. Their recoil-lug sockets line up fine, but the factory screws are too thick for many standard Docter adapter plates. If you’re mounting one of these to a Docter-pattern plate, confirm screw compatibility first — you may need thinner aftermarket screws.
Crimson Trace: CT Rad and CT Rad Micro Footprint
Crimson Trace red dots use the CT Rad Micro footprint, which is compatible with the Shield RMS footprint. The CT Rad footprint is compatible with the Docter footprint as well.
Sig Sauer Sig-Loc
Sig developed the Sig-Loc system for the M17 line of handguns but has now extended that system to other models as well. What’s unique about this system is that it allows an optic to sit directly on the slide and is secured by screws from underneath the slide. The SIG-LOC system uses five points of contact for what they claim is one of the most secure mounting systems.
Right now, the only optics that use this footprint are the Sig Romeo X line of optics. However, Sig provides adaptor plates so other popular footprints can be used on their handguns.
HEDS Direct Strike Magnetic Mount
While it’s not a footprint, this new system from HEDS is worth mentioning for those who have handguns that are not optics-ready.
As we have been discussing, a handgun needs a cutout on the slide with an optic that has a matching footprint or an adaptor plate, right? Well, HEDS has created a system that uses a magnetic mount to attach an adaptor plate to a gun that doesn’t have any cutouts.
HEDS has created a plate that is magnetic and fits over the rear sight of the handgun and then “snaps” into place on the slide.
When I first saw this at SHOT 2025, I was positive it would not stay on the gun. However, I spent some time on the range with one and was surprised to see it worked great. They even hit the optic on the side of the counter to rack the slide to show how strong the connection is.
Is direct mount the way of the future?
Some people love handgun-mounted optics, and others do not. But either way, they are becoming the way of the future. We saw trends of new optic footprints for a while, but now the trend appears to be direct-mount options that use traditional footprints like RMR and RMSc.
I like this trend because it allows us to continue using optics we already have without buying more adaptor plates (or worrying about new optic footprints).
Adaptor plates create a weak point for the optic and place a lot of pressure on the screws. Screws hold down the adaptor plate, and more screws hold down the optic. When the optic is screwed directly to the slide of the gun, you eliminate one whole set of screws.
Either way, if you are going to use an optic on your handgun, make sure you are aware of the footprint or mounting system that the gun uses. This will allow you to select an optic that uses the same system. With companies like Glock, you will be able to mount the most popular optics on them. Other manufacturers, however, mill the optics cutout on their guns for a specific footprint. And given the proliferation of available optics, it’s always a good bet to check the most current red dot footprint chart you can find.
