I am reloading Browning 300 win mag brass that is over 20 years old. They are loaded HOT,and are giving me no grief at all. I strictly neck size, and anneal when needed. Each rifles is custom trimmed to the chamber dimensions, which in turn, prevents unnecessary stretching of the case. If you full length resize after every firing, you are working your brass, moving the shoulder back,hardening it and shortening it's life considerably. You are also making it flop around in the chamber and this can and will be an accuracy wrecker. When you fire it, it will expand to your chamber specs, giving a good fit. Then, it's back to the bench and worked back to minimum specs again. Not good! Neck size it, and it will last a LONG time.