I don't have a problem using shims under the lock ring on my co ax. I refuse to use shell holders,that what drew me to the co ax. No shell holders.[/
You need to also look at how thick the rings are from one to the other some are a big deference that the ring is hitting back in fourth on the top and bottom of the grove .
I have heard this n I heard that but I think I'm staying with what is made for the press.
I just bought a Widden die set (new) one of there rings fit real good the other one is .017 thinner than the other .
Robert