James the gun they are being installed on determines the amount of fitting. On the ProSport all the stock surfaces are relatively flat and the only fitting is getting the counter bore the correct depth. I generally try to counter bore to the depth of the existing screw hole so not to lose any strength but if the existing hole is deeper than the length of the escutcheon I fill the bottom of the hole with JB Weld.
On your R1 the screw hole is on a radiused part of the forearm and will require some hand fitting. Counterbore the hole so the escutcheon sits flush at the top and it will be a little proud at the bottom. Mask around the escutcheon with masking tape and file to fit the radius. The screw heads can be fitted by chucking the screw in a drill and filing to a flush fit.
Here is a pic of my R1 that I used SS screws on.
Charter member of Over The Hill Gang