While WalkAlong is correct, you can get good case life with FL sizing, the Lee collet die does make things a bit easier in that you do not have to lube the cases and case mouth to resize the neck. An additional benefit I have found is that if you follow directions and size cases twice, once and turn 90 degrees and size again, after a couple of trips through the collet die and your cases will have uniform neck thickness without having to turn them to get them the same thickness. A fire-formed case will self-center in your chamber and give slightly better accuracy assuming you are shooting the brass in the same gun. If you have a semi-auto .30-06, follow Walkalong's advise and full length resize. With a bolt gun you can take advantage of the Lee Collet die for better accuracy. While you are at it, consider the Lee Factory Crimp die which can also give you an extra edge if used properly