I have only ever loaded for a friends 300WSM, it was very difficult to size after a few firings as you've discovered.
Are you 'camming over' on the press?
I found that you had to screw the die in until it made contact with the shell holder and then raise the ram and screw the die in another 1/4 turn to size the cases enough for them to chamber correctly. I had several attempts until I got the bolt to close with little resistance.
PFL sizing was practically useless, and they had to be FL sized due to the expansion just above the web, the brass is very hard in this area and tends to 'bounce back' after sizing.
Give it a go in your rifle, FL size gradually deeper until you get the bolt to close with little resistance.