Pull a bullet and measure at/below the crimp line, if it's less than .356 you are resizing the bullet with too much crimp. Also measure a loaded round at the case mouth. As others stated you should be .377, I run .378 with no issues with set back or case gauging. Also case gauge EVERY round just to be certain that is not playing into this issue. Your OAL of 1.14-1.15 may be short enough but maybe not. In my Shadow I have to run ACME 124's at 1.060". Your max oal's seem overly long to me but it is possible I guess.
As as far as cleaning. I go thousands of rounds before seeing issues. Also why Copper Remover? You are only shooting lead bullets.