# What red dot fits a SIG P365 without an adapter plate?

**Verdict: Yes**

Anything cut for the Shield RMSc footprint. The optic-ready P365 slide is milled for it, so RMSc-pattern sights mount straight on.

The optic-ready P365 slide is milled for the Shield RMSc footprint, so an RMSc-pattern sight seats on it without an adapter plate. That covers the Shield RMSc and SMSc, the Holosun 407K and 507K, the SIG Romeo Zero, and the Swampfox Sentinel among others.

- **Slide footprint** — Shield RMSc
- **Adapter plate** — Not required for an RMSc optic
- **Mounts directly** — Shield RMSc / SMSc, Holosun 407K and 507K, SIG Romeo Zero, Swampfox Sentinel
- **Screws** — Match to the slide, not to the box — see the caution below

Worth knowing if you have read that a Holosun K optic needs an adapter plate: that advice comes from the Glock Slim MOS cut, not from this one. Both are described as RMSc, and they are machined differently — which is why the same optic can be a direct fit on one pistol and not another. Do not carry a conclusion across from one platform to the other, in either direction; look at the slide in front of you.

> **Caution:** Screws are the part that bites here, and they are not a detail. The P365 slide is tapped M3 x 0.5, while Holosun K-series optics ship with M4 screws in the box — which is why several makers sell P365-specific screw kits. Worse, the extractor spring channel runs beneath one of the optic screw holes, so a screw that is merely too long can bind the extractor and stop the pistol working. Use screws sized for the slide, check the length dry before torquing, and if an optic came with hardware for a different pistol, do not use it.

## Sources

- [Shield Sights — maker of the RMSc the footprint is named for](https://www.shieldsights.com/)
- [Holosun HS507K X2 product specifications](https://www.holosun.com/products/hs507k-x2)

## More on optics and mounting

- [Does a Trijicon SRO fit an RMR cut?](https://www.tactgpt.app/answers/trijicon-sro-rmr-same-footprint.md)
- [Will a Holosun 507K fit a Glock 43X MOS?](https://www.tactgpt.app/answers/holosun-507k-glock-43x-mos.md)

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Last checked 2026-09-02. TactGPT can make mistakes. Always check important info for accuracy. The information it provides is intended for educational purposes only. It does not give legal advice; verify any laws cited. Always follow all applicable laws and safety guidelines.

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