20 plus years ago I bought an RCBS .45 ACP die set. It worked great until I got hold of some Remington brass. I had the same problem you have. It would not size Remington brass enough. I called RCBS and they sent me another sizer. This one was very tight, but it worked with Remington brass. I only used it for that and continued to use my original for everything else. Then a few years ago I bought a Redding sizer. It is right in between the two RCBS sizers. I use it for everything now. I load a horrid mix of range brass with no troubles.