If you are collapsing the shoulder of the case you need to turn the seater die out about 1/2 turn and then adjust the seater plug in to get the right seating depth. You should not need to crimp for the 308 in a bolt gun. If the dies are correct and all cases are trimmed to the same length you should be good to go. If the cartridges are loaded correctly you should not be able to move the bullet in the case.