I have the wilson for 30/30, just one rifle but the chamber is longer than spec. I use feeler gauge on the case gauge to measure the case head protrusion to set the sizing die. Necks never seem to get long. If the shoulder isn't too different, just set for the shortest and check for case web wear. I got a bucket of fired and 6-7 boxes of factory ammo for cases. I case check for 308 as they are autoloaders and it get bad if they aren't correct. None will really check case/neck diameter.