There are times the press whips the case, there are times the case whips the press, I sent a new Mod 70 Winchester chambered in 300 Win Mag back to Winchester, it had the ugliest chamber I have ever seen, it was too long and too large in diameter, the scary part, they informed me they would hone, polish or ream the chamber, first locally, and if that did not work the rifle would be sent to where ever, and I ask:
"What is it about honing, polishing or reaming the chamber that is going to make it smaller", long story. Something foreign to reloaders/smiths is datums, I use datums, Winchester never ask me how I knew their Sammy chamber was junk, they assumed I did not have a clue, back to sizing, you did not say what press you are using. Mothering dies as in "I clean my dies with a de-greaser that is used to remove grease from brake parts", I do not do that, I clean my dies with a towel on a dowel, because I want grease and or lube in my dies so I ask myself, "Is there harm in removing that slick stuff from the inside of my dies" I had thought I had purchased my last set of dies but I got a deal on 4 very heavy barrels and I found a discount on a set of limited edition RCBS dies and that was all the excuse I needed, I cleaned the inside of the dies with a towel on a dowel, the finish inside the die is as good as it gets so I apply the 'leaver policy' I leaver the way I founder.
You say the FC cases are crushing, to me that sounds like the press is winning, I would be hard pressed to find a set of cute dies in my possession, my dies are straight forward 'versatile' full length sizer dies, my full length sizer dies size cases for short chambers, .012 thousands shorter than a full length sized case (minimum length) to infinity beyond a go-gage length chamber, or a more practical neck sizing without case body sizing, there again If I could bump??? I could do it with case body support, but that is a concept that is foreign to reloaders. Bump sounds like an accident so I choose case forming, until the definition of bump allows a reloader to go from 'bump' to form as in 'Forming begins after the shoulder has been bumped back .005 thousands'.
Crushing cases, I do that to determine the cases ability to be sized, I turn a forming die upside down in the press, as in screwing it into the press from the bottom, I install a case in the shell holder and raise the ram, the neck of the case inters the die and the case is crushed between the shell holder and and die, a good case will fold like an accordion/bellows with out folding or splitting.
Back to the 300 Win Mag, it would have been mindless to size the case with a full length sizer die, when I purchased the rifle I wanted a rifle with a chamber that would fit my dies, after I determined the chamber was too large for my dies I wanted the next best thing, I wanted a set of dies that would size cases to fit Winchester new creation (a chamber that did not fit my dies), so I took the rifle to their warranty shop, sure enough he reamed, polished and honed, guess what, the chamber got bigger, and he said "They made me do it".
F. Guffey