Hi new to your Forum Just bought a new Sig p226 X5 wanting to install a new Trijicon SRO red dot. Do I need a mounting plate? I assume I do from what I've read. like what springer makes???

Does your slide have two sets of screw holes? If so, one of them is likely for the RMR footprint that the SRO utilizes. If that's the case, you may still need a "filler plate" to take up the space between the optic and the edge of the slide cut. Something like this: https://shop.springerprecision...p320-p226-r2-slides/

If your slide only has one set of screw holes, those will be for a Deltapoint Pro footprint, and you'll need an adapter plate for your SRO. Something like this: https://shop.springerprecision...r-sig-sauer-p226-x5/