This must surely have come up before, but I can't find anything that relates?
I'm loading the Lee 405 gr HB into Starline cases. Bullets mic at .460 just like they should. Case is .457 neck. 1/5 of the bullets pop back up .01 or so, and I can compress them with finger pressure against the air pressure under them. What's the solution? That neck tension should be fine, and short of getting a custom die I can't make it tighter...
No such issue with Lyman 535 Postells, also measuring . 460