A Guide to the Most Common Red Dot Footprints

When mounting a red dot sight to your firearm, understanding the "footprint" of the optic you want to mount ensures it fits properly and works on the firearm. The footprint needs to match the slide cut or the mount that you want to attach the optic onto. The footprint is the pattern of the underside of the optic produced by its shape, screw pattern, and recoil lug holes. There are many footprints that optic manufacturers produce and utilize to tailor their optics to a specific portion of the market.

Certain footprints are used more commonly while other footprints are exclusive to an optic or manufacturer. This is why optic plate systems like the Modular Optics System (MOS) and Airborne Optical System (AOS) are beneficial, as they allow you to change the optic footprint for your gun. If you're trying to find which footprint you have or need for your firearm, here are some of the most commonly used footprints, as well as some popular optics that share the same or similar footprint. 

Trijicon "RMR" Footprint

The Trijicon RMR (Ruggedized Miniature Reflex) footprint is arguably the most common footprint on the market today, and it was first introduced by Trijicon upon production of their red dot sight with the same name. Many people confuse pistols optics in general and refer to all pistol optics as "RMR’s" which can lead to confusion as not all optics share the same footprint. The RMR footprint consists of 2 screw holes and 2 front recoil lug holes in the corners. Some slides or plates will have recoil lugs to utilize the matching holes on the optic while other designs do not. Optics that utilize this footprint include:

• Trijicon - RMR and SRO
• Holosun – 507C, 407C, 508T, 507 Competition
• Swampfox – Kingslayer, Liberty, Justice
• AmeriGlo – Haven
• Riton Optics – X3 Tactix PRD
• ADE Advanced Optics – RD3-020 Raptor and RD3-023 Valkyrie
• SIG SAUER – Romeo Zero-R
• Primary Arms – Classic Series Mini Reflex Sight

Docter/Noblex Footprint

The Docter/Noblex footprint was very common in the earlier days of pistol slide mounted optics. It utilizes 2 screw holes and 4 sockets to accept recoil pins. Most optics that used the Docter footprint have been discontinued or modified to use more common footprints. However, there are still some red dot sights that utilize this footprint and remain popular today. These include:

• Burris – Fastfire 2, 3, and 4
• Hex – Dragonfly
• Vortex – Viper, Venom
• Primary Arms – SLx RS-10
• Leapers UTG – OP3 Micro
• Hawke Sport Optics – Reflex 1x25

C-More Footprint

The C-More footprint was developed by C-More with their popular RTS and STS red dot sights. While there are not many modern offerings for this particular footprint, it is still used today. It features 2 screw holes and 2 sockets located in front and in line with the screw holes to accept recoil pins. Optics that use this footprint include:

• C-More – STS, STS 2, RTS, RTS 2
• SIG SAUER – Romeo 3, Romeo 3 MAX, Romeo3 XL
• Vortex – Razor
• Vector Optics – Frenzy 1x26

RMSc Footprint

The "RMS/c" footprint is similar to the Docter pattern footprint using 2 screws holes with 4 sockets in each corner to accept recoil lugs/pins. However, the sockets are wider and closer together than Docter footprint optics. An important thing to note about this footprint is that there are 2 sizes of optics that utilize this footprint. Micro optics like the Shield RMSc and SIG SAUER Romeo Zero utilize the RMSc footprint and measure approximately 40mm in length. Larger optics like the Leupold Deltapoint Pro and SIG SAUER Romeo 1 Pro also utilize the same footprint but measure up to 46mm in length.

If your optic-ready pistol slide is designed to accept RMSc footprint optics, they are referring to micro-sized optics like the SIG SAUER Romeo Zero. If your optic-ready slide states it is designed to fit optics with the Deltapoint Pro footprint, then you need to use the full-size optics that share the RMSc footprint. Optics that use this footprint include:

• Shield Sights – RMS, RMSw, RMS 2, SMS, PMSx, SMS 2.0, RMSc
• SIG SAUER – Romeo Zero, Romeo Zero Elite, Romeo 1 Pro, Romeo Zero Pro
• Swampfox – Sentinel
• Leapers UTG – OP3 Mini Micro
• Vortex – Defender
• JP Enterprises – Jpoint
• Primary Arms – Classic Series 21mm Micro Reflex Sight

Full-size optics that utilize this footprint include:

• Leupold –Deltapoint Pro
• EOTech – EFLX
• Holosun – SCS 320

Glock MOS

The Glock MOS cut (Modular Optic System) is proprietary and designed to be used with adapter plates allowing the user to install optics that fit the included adapter plates. There are 2 screw holes located between the front and the middle of the mounting surface. While this cut was initially designed to use adapter plates, Holosun makes an optic that will mount directly to the optic cut without the need for a plate.

• Holosun – SCS MOS

Aimpoint Acro Footprint

Aimpoint designed a mounting footprint specifically for their ACRO series optics. It uses grooves on the side of the footprint with a moveable "lug" that is tightened down to clamp the optic to the mount. The movable lug is connected to a recoil lug that extends from one side of the base to the other. It is similar to a picatinny mount but is not the same, and will not fit picatinny rails. Optics that use this footprint include:

• Aimpoint – Acro C-1, Acro C-2, Acro P-1, Acro P-2
• Steiner - MPS

Aimpoint Micro Footprint

Aimpoint developed the "Micro" footprint for their small tube red dot sights. Many other manufacturers have adopted this footprint for their small tube sights as well making it the most popular option for tube style optics. It uses a raised middle section with 2 screw holes on either side. In the raised middle section, a recoil stop is cut into the optic footprint. Some optics that utilize this footprint include:

• Aimpoint – CompM5, Duty RDS, CompM5b, Micro H-1, Micro H-2, Micro T-1, Micro T-2
• Holosun – 403B, 403C, 403GL, 403R, 503BU, 503C, 503CU, 503FL, 503G, 503GU, 503R, 515C, 515CM, 515CT, 515GM, 515GT, 530C, 530G
• Primary Arms – SLX MD-20, SLX Advanced Rotary Knob
• SIG SAUER – Romeo4, Romeo5, Romeo-MSR
• Swampfox – Liberator
• Vortex – Crossfire, Sparc AR, Sparc Solar
• Bushnell – TRS25

Shop Red Dot Sights & Mounting Systems at OpticsPlanet!

Understanding the optic footprint for the optic you have, or the optic you wish to purchase, ensures you find the correct adapter plate, mount, or optic-ready slide to fit the optic. Some optics use proprietary footprints, such as the Holosun 509T, which will not fit directly to any common optic cut. However, proprietary optics typically include an adapter plate that allows you to mount the optic to a specific optic cut. In this case, the 509T includes an RMR adapter plate that will bolt to RMR cut slides and RMR mounts, which then allows you to install the optic. Holosun also designed a footprint similar to the Shield RMSc footprint known as the Holosun K footprint. This footprint is a slightly modified version of the RMSc footprint. Check out our Holosun K Red Dot Footprint Guide for more information about this option.

While there are many optics with many different footprints available on the market today, as long as you understand what footprint your optic of choice uses, it is easier to find compatible mounts and adapter for it. The same goes for those who have an optic ready slide looking for an optic. If you know your slide has an RMR cut, you can now narrow down your options and understand what optics will be able to directly mount to your slide. And to make it even easier, we have tons of red dot sight mounts available right here at OpticsPlanet! Also, check out our guide on the Most Popular Optic Cuts for Pistols to learn more about the benefits and uses of the different types of optic footprints.