Yes, the Trijicon RMR/SRO Adapter Plate for the P320 X-Carry (MPN:AC32088) will be compatible with your Full Size P320. The only reason another plate exists for the M17 is due to the LCI on the M17.
There are certain Sig Pro Cut Slides that allow for the RMR to be mounted to them using only a sealing plate. The Trijicon RMR/SRO Adapter Plate will work for mounting the RMR to the listed P320 models on the product page. Please email us at techsales@opticsplanet.com so we can get more information regarding your specific slide.
Yes, this Trijicon RMR/SRO Adapter Plate will fit the optic cut on an P320 M17 or P320 X-Carry model pistol and convert it to accept optics with the Trijicon RMR footprint.
No. The P320 X-TEN is dual cut from the factory to accept DeltaPoint Pro and RMR footprint optics. To fit an RMR pattern optic, all you would need is a sealing plate like the one linked below:
https://www.opticsplanet.com/trijicon-rmr-mount-sealing-plate.html
You would have no need for this adapter plate. Since you have the Dual-Optic cut you can already fit optics with a Trijicon RMR footprint and optics with the Leupold Deltapoint Pro footprint.
The Trijicon RMR/SRO Adapter Plate for the Sig Sauer M17 (MPN:AC32087) is also compatible with the M18. The M18 shares the same exact optic cut dimensions at the M17.
Yes, the Trijicon RMR/SRO Adapter Plate will work for mounting the 507C to the Sig M17 or M18.
The Holosun 508T uses the RMR footprint. So the Trijicon RMR/SRO Adapter Plate for the M17 will work with the 508T.
These Trijicon RMR/SRO Adapter Plates are for Sig Pistols with an optics ready slide. They will not work for a Glock. Also from what information I could find the MS03 red dot uses the JPoint mounting footprint. If you need a dovetail mount for your Glock the mount at the link below might work.
https://www.opticsplanet.com/evolution-gun-works-leupold-deltapoint-pro-sight-mount-for-glocks.html