Sig M17 / P320 Cut Dimensions

A Comprehensive Guide to Sig Sauer P320, M17 & M18 Optic Cuts

The Sig Sauer P320 platform, including its military counterparts the M17 and M18, has become exceptionally popular for its modularity and performance. A key feature for modern shooters is the ability to mount a red dot sight, but navigating the world of optic footprints and slide cuts can be confusing. This guide will demystify the factory optics-ready cuts on these popular Sig pistols to ensure you find the correct mounting plate for your firearm.

Non-Optics Ready? No Problem.

First, if your Sig P320 slide is a standard, non-optics-ready version, you can still mount a red dot. This is achieved using a dovetail mounting plate. These mounts slide into the factory rear sight dovetail, providing a secure platform for your optic. You can explore our full range of dovetail mounts for various red dots here.

Understanding the Two Main Optics-Ready Cuts

We currently manufacture mounting plates for the two primary optics-ready slide cuts offered by Sig on the P320 and M17/M18 series. It's crucial to identify which one your pistol has.

1. The Sig P320 RX (Romeo1) Cut

This was the earlier optics-ready cut found on models designated as "RX." It was specifically designed for the original Sig Sauer Romeo1 red dot.

Key Features:

• Mounting screws are #6-48 TPI.
• This is a dedicated cut primarily for the original Romeo1 footprint.

Our P320 RX Mount (SKU 49200) is designed for this specific cut and provides a platform to mount other popular red dots. This mount is confirmed to fit the following models:

• Sig P320 RX Optics Ready (Romeo1)
• Sig X-Five Optics Ready (Non-Legion models with the Romeo1 cut)
• Sig P320 X-Carry (with the Romeo1 cut)

2. The Sig M17 / P320 R2 (Romeo1Pro / Deltapoint Pro) Cut

This is the modern, more versatile cut found on the current P320s, as well as the M17 and M18 pistols. It is milled to directly accept the Sig Romeo1Pro and the Leupold Deltapoint Pro. This cut is sometimes referred to as the "R2" cut.

Key Features:

• The rear mounting holes are drilled and tapped for #4-40 screws.
• Crucially, your slide must have these rear holes for our adapter plate to function. The mounting screws for our plate are accessed from the underside of the slide.
• The cut depth on the M17 is approximately .047" with a flat rear shelf.

This cut is found on models such as:

• Sig M17
• Sig M18
• Newer P320 models with the Romeo1Pro / DPP cut

Important Exclusions

Please be aware of the following compatibility issues:

• Our P320 / M17 mounts that fit the Romeo1Pro and Deltapoint Pro cut currently do not fit any models with a loaded chamber indicator or a dovetail rear sight integrated behind the optics cut.
• We do not manufacture a mount that fits the P320 M17 Decommissioned Military version. This version has unique mounting hole placements.

Choosing the right mount is essential for a secure and reliable optic setup. By carefully inspecting your slide and understanding these key differences, you can confidently select the correct EGW mounting plate for your Sig Sauer pistol.