Holosun 507C: What Pistols Fit It, Directly and With a Plate

The Holosun HS507C-X2 fits 117 optic-ready pistols in our data. Seven of them take it with no plate. The other 110 need one. The reason comes down to a single fact about the optic: the 507C sits on the RMR footprint. Once you know that, the whole compatibility question gets simple, because “what fits the 507C” is really “what is cut for the RMR.”

What footprint does the 507C use?

The RMR pattern, the mounting standard Trijicon built for its RMR optic. Two screws, two recoil lug sockets at the front, and that is the interface. The 507C copies it, which is why a 507C drops into the same slide cuts, plates, and holsters as a Trijicon RMR.

That footprint is popular. 47 optics in our data use the RMR pattern, and 26 of those are Holosun. So the 507C is just one of dozens of sights that share that base, and it inherits the RMR pistol list wholesale.

Which pistols take a 507C with no plate?

Seven, and they have something in common. The Anderson Kiger-9C Pro, both Lone Wolf models (the Dusk 19 and the LTD19 V1), the Ruger RXM, the Shadow Systems MR920, and two Tisas PX9 pistols.

Look at what is missing. No factory Glock. No Sig. No factory Smith and Wesson. The RMR cut shows up almost entirely on aftermarket and clone slides built for the Glock platform, where the slide maker picked RMR because the optic selection is so deep. If your slide is one of these seven, you buy the 507C, bolt it down, zero it, and you are done.

What about every other optic-ready pistol?

You use a plate. The 110 pistols that need one run across 12 brands and 15 different plate systems. Glock MOS, the Sig P320 X-series, the Smith and Wesson M&P CORE, the FN 509 system, Walther PDP, Canik, CZ, HK, and more all have a plate that presents the RMR pattern on top.

The rule is the same every time. The plate bolts into your slide’s real cut, and the 507C bolts to the plate. You add a little height and one more set of screws, so torque it to spec and use thread locker. Done right, it holds zero fine. Almost every optic-ready pistol on the market has a path to a 507C, and only a handful skip the plate.

What do X2, X3, and GR or GD mean?

The 507C ships in several flavors, and the names look busier than they are. HS and HE mark the two emitter lines. X2 and X3 mark the generation. Suffixes like GR, GD, and RD flag the reticle color and options.

Here is the part that matters for fit: none of it changes the footprint. Every 507C variant in our data, X2 or X3, HS or HE, sits on the RMR pattern and fits the same 117 pistols. Pick the variant you like on reticle and price. The mounting answer does not move.

The one name that does change the answer is the 507K. Drop the C for a K and you leave the RMR footprint entirely for the smaller Holosun K pattern. That flips the whole list. The 507K fits 26 of the 27 pistols in our set directly, the mirror image of the 507C, because compact carry guns tend to be cut for the K and full-size RMR cuts stay rare. A 507C and a 507K are not interchangeable on the same slide.

How do I check my specific pistol?

Look it up by exact model. Every pistol page here lists the footprints that gun accepts and marks each optic as a direct fit or a plate fit, with a source on the fit. Start with your real slide, not a close cousin, because a plain Glock 19 and a Glock 19 MOS behave differently at the top.

The short version: the 507C is an RMR optic. Seven pistols take it bare, and the rest take it on a plate. Confirm your cut before you spend the money, and the 507C will mount to almost anything you own.