I agree that you are best to resize if you have the time. Using the same hulls in the same gun would probably negate the need to resize. But I run all hulls through my MEC Supersizer, before reloading. DTrkow, in a MEC 650 there is no resizing operation. Also, with a Hornady 366 the resizing is a separate station. I use a 366 and by running all hulls through the Supersizer, I can skip that station. Resizing just gives me "peace of mind", even if I shoot them in the same gun all of the time. If you ever have problems on the line due to the shells not going into your gun; you will definitely experience extreme frustration. Been there and done that. Ed