OPF-G, RMR's front and rear recoil fences/lugs are designed to snugly cradle the sight in between.
The design replicates the effect of a milled slide, wherein the sight is neatly sandwiched between barriers and unable to move along the bore. The design also quite effectively limits the sight from rotating on the OPF-G, RMR. In addition to the side by side recoil lugs for the RMR, the front and rear recoil fences/lugs prevent the sight from twisting on the plate.
Trijicon RMR recoil lugs have a +/- 0.005 tolerance, the fit between the sight and plate can be very tight. The tight fit is by design, a sight that won't move on the plate before the screws are installed won't press the screws into service as recoil lugs, a task fully threaded screws are uniquely poor at, and in this case, not designed to perform. Loosened and eventually sheared screws have little to do with the screws themselves, rather, it's the misuse and abuse of them by flawed designs that fail to grasp the concept of right tool for the right job, RMR mounting screws are not recoil lugs, they fail when used as recoil lugs.
OPF-G, RMR uses the area between the recoil lugs and the front fence/lug to hold the RMR immobile. Often, only a firm press with both thumbs on the sight onto the plate (with the plate installed on the slide) is required. In rare cases, the inside corners of the front recoil fence may need to be fitted.
Below is our test RMR, note the area in the front corners of the sight where the plate's front fence makes contact with the sight. This is normal. We don't solely rely on tight tolerances of recoil lugs on our plate to deny the sight movement in recoil, the front fence serves as a secondary lug.
If your RMR is on the + side of the tolerance (up to 0.005 is still considered within spec) and a firm press with both thumbs still won't fully seat the sight on the plate, minor fitting of the plate in the area below may be necessary. Users have used a mallet to pound the sight onto the plate, we don't suggest it, though the RMR will simply shrug it off.
Use a Dremel tool to remove about 0.001 to 0.002 of material in the area circled in red. Remove a tiny bit at a time, evenly on both sides of the fence, and refinish with cold blue so it will not rust.