In this guide, we will explain the footprint and mounting of the Sig Sauer Romeo X Compact red dot so you can be sure that it is compatible with your pistol.
Red dots are not made to a particular industry standard, so it is important to know which red dot is compatible with the handgun you want to use it with.
We will cover what to look for on your existing handgun and the specifics of the Sig Sauer Romeo X Compact mounting footprint.
Optics Ready Handgun
First, your handgun must be optics ready to mount a red dot to the slide. Handguns that are optics ready typically come with cover plate on the slide near the rear sight. This cover plate covers the red dot mounting surface when a red dot is not being used. In some cases, the cover plate may include the rear sight.
In the picture below the two handguns on the left are optics ready, while the handgun on the right is not.
The mounting pattern that is machined into the handgun slide for the red dot is called the mounting “footprint”. This footprint is not an industry standard and can vary between handguns and red dots. Check the manual that came with your handgun for details on how to remove the cover plate and what red dot footprint your handgun has. Also compare it to our photos below.
Handgun Size
Next, it is important to understand if your handgun has a “full-size” slide or a “compact” or “slim” slide.
Full size handguns typically have a slide that is about 1.0 to 1.1 inches wide. Some examples are the Glock 19, Walther PDP, and Sig Sauer P320.
Compact size handguns typically have a slide that is about 0.8 to 0.9 inches wide. Some examples are the Sig Sauer P365, Glock 43X MOS, and the Springfield Hellcat.
In the picture below, the handgun on the left is a full-size (Walther PDP) with a Holosun 507C. The handgun on the right is a compact (Sig P365 X-Macro) with the Sig Sauer Romeo X Compact.
Note that there are two versions of the Romeo X red dot. The Romeo X Compact is a compact size red dot intended for smaller compact handguns. The Romeo X is a full-size red dot intended for full-size handguns. If you have a full-size handgun, consider the Romeo X instead, not the compact version.
The Sig Sauer Romeo X Compact Mounting Footprint
The Sig Sauer Romeo X Compact has the popular RMS (or Shield) footprint. The RMS footprint has four posts, one in each corner, and two screw holes near the rear of the sight.
In the picture below, you can see the footprint on the Sig Sauer Romeo X Compact next to two compatible handguns.
Most compact handguns are compatible with the RMS footprint. Some handguns like the Sig P365 (on the left above) have a modified version of the RMS footprint with no posts and only raised lugs around the screws. This optic is also compatible with these handguns and does not require an adapter plate.
Will the Sig Sauer Romeo X CompactFit your Handgun?
The Sig Sauer Romeo X Compact will fit any compact handgun that is optics ready and has a compatible RMS (or Shield) footprint. Almost all optics ready compact handguns are compatible with this optic.