After i shoot a box of new win 270 WSM brass in my model 70 they chamber with very little resistance(just alittle bit more than new). I can just barely feel the fired cases contact the inside of the chamber when i close the bolt. After I neck size them, even if ijust go about halfway down the neck, with my RCBS FLS die, the cases are very tight in the chamber. Why would they be tighter in the chamber after neck sizing than before? Is it possible that when the die sizes the neck, it is also contacting the body further down the case and somehow pushing it out?? I am very confused about this. If I screw the die down to where it touches the shell holder and totally full length size the cases, they will chamber with no resistance, but they are very very tight anything short of full length sizing. Whats going on? What can I do? Thanks.