In this guide, we will explain the footprint and mounting of the Holosun 407C, 507C, and 508T red dots so you can be sure that they are 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.
The Holosun 407C and 507C are part of Holosun’s C series of red dots. They both have the same dimensions, with the only difference being the type of reticle. The Holosun 508T is a rugged Titanium version of the 507C and has the same mounting footprint.
We will cover what to look for on your existing handgun and the specifics of the Holosun 407C, 507C and 508T 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 handgun 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 full size (Walther PDP), and the handgun on the right is a compact (Sig P365).
The Holosun 407C, 507C, and 508T are all full-size handgun red dots intended for handguns with full size slides. If you have a compact handgun with a slim slide, consider the Holosun 407K or 507K instead.
The Holosun 407C, 507C, and 508T Mounting Footprint
The Holosun 407C, 507C, and 508T have the standard RMR mounting footprint. This is one of the most common footprints for full size handguns. It has two posts on the front and two screw holes near the center.
In the picture below, you can see the RMR footprint on the optic plus two handguns with RMR footprints.
Many full size optics ready handguns like the Glock MOS and Walther PDP have proprietary footprints that require adapter plates. Some come with adapter plates included, while others must be ordered separately.
For example, The Glock 19 MOS handgun comes with an RMR adapter plate. So, these optics will mount directly to it without the need for a separate adapter plate.
The Walther PDP does not come with any adapter plates, but they can be ordered directly from Walther (the first one is free). Simply select the “RMR” plate when ordering.
For your handgun, consult the manual and compare it to our picture of the RMR footprint above. If your handgun does not have a RMR compatible plate or slide, we have the following adapter plates available:
- Sig P320 RX Series/Pro Series/AXG Scorpion with Delta Point Pro footprint
- Sig P320 X-Five/M17/M18 with Romeo1 Pro/DPP Footprint
- CZ P-10 V4
- H&K VP9 (2020 and newer)
- S&W M2.0 C.O.R.E
Will the Holosun 407C, 507C, or the 508T Fit your Handgun?
The Holosun 407C, 507C, and 508T will fit any handgun that is optics ready and has a compatible RMR footprint. Some handguns that have a proprietary adapter plate system or are cut with a different footprint may need an adapter plate.