(I would just ignore the full-length die)
At some point you will have to use your FL die as the brass case will continue to grow with each firing and neck sizing.
Is your 308 a bolt action? If so then crimping is not necessary as neck tension is all that is required to secure the bullet.
If it is a semi-auto then you have to forget the Neck dies and FL size every time. I would also recommend a Lee Factory Crimp die for a semi-auto. It not only secures the bullet it improves accuracy.