I have a number of Super Redhawk and GP100 revolvers, and all have benefitted from the installation of shims. The shims that I use are:
Shim Flat Washer, 18-8 Stainless Steel, 3/32" Bolt Size, 0.093-0.098" ID, .198-.208" OD, 0.002" Thick (Pack of 25)
and
C1074/C1095 Spring Steel Round Shim...