No it will not, this slide is only 4.7" long.
The SIG SAUER Pro-Cut 4.7in Slide Assembly is compatible with the M18. However, you will need to use a 4.7" barrel and full size recoil spring.
The Sig Sauer 8900953 OEM Replacement 9mm Luger For P320 (4.70" Barrel) at the link below will work with the RMR but will need a sealing plate.
https://www.opticsplanet.com/sig-sauer-8900953-oem-replacement-9mm-luger-for-p320-4-70-barrel-pro-cuts.html
The SIG SAUER Pro-Cut 4.7in Slide Assembly has an optics cut to fit the Sig Romeo1 Pro and Leupold DeltaPoint Pro.
We currently carry the 4.7" and 3.6" versions.
This slide will work with any full size p320
Pre-Installed Front & Rear X-Ray3 Nights Sights
R2 Optic Ready - ROMEO1 Pro & Delta Point Pro
Rear Sight Cover Plate
Striker & Extractor Assembly
Steel Constructed Slide Body
Coyote Brown Finish
Serrated Grooves
Stylish Relief Cuts
For 4.7" 9mm Barrels, P320 Full Size
Yes, this slide works on all full size p320 handguns including the p320 m17
The MCK is not compatible with factory night sights, so no.
Pictures currently on the site are accurate.