Welcome to the campfire! Something to consider, since you already have the bushing die and have ordered the collet die is that they can be used in tandem. You can use the collet die for sizing the necks very concentrically and bump the shoulders as needed with the bushing die minus the bushing.
You can also size the necks to your desired diameter, plus 2 or 3 thousandths with the collet die and then use your bushing die for the final neck sizing and shoulder bump operation with a bushing installed and the expander removed. This can work very well if your brass has uniform neck thickness and provide repeatable and consistent neck tension and concentricity in my experience with a
.308 Win.
