Home Forums Hunting & Shooting Ask The Gunwriters sizing brass

I am not new to reloading, but certainly not a guru. Sometimes when sizing brass like the 300wsm brass I was sizing this morning, will fit tight in my chamber, (ie) tight bolt close.
This brass is all same manufacture, all ran through same RCBS FL die, all trimmed to same length, and some the bolt will nearly fall on its own. Some will be somewhat hard bolt close and some will be hard bolt close.
This is Winchester brass, some once fired by my rifle and some once fired in a buddy's rifle. I wouldn't think if it was fired in another rifle would make any difference when FL resizing.
Any ideas ????