The RCBS Precision Mic will also help you in that department (if you have a factory cartridge). I've been using them in 223, 22-250, 220 Swift, 243, and 25-06 for about 17-18 years now. They cost about $50, and well worth the money IMO.
You might also try just neck sizing until the fired brass gets slightly tough to chamber......that's where the shoulder bump comes in. If the cases haven't stretched enough to fill the chamber yet, and you're bumping the shoulder and FL sizing already, it could cause problems like case head separation.
Not saying it will, just saying it could. I had that problem with my 220 Swift. That's when I found the Precision Mic and Neck sizing dies. Happily ever after.