Started with new 458 cases at 2.50. Resized to 416 Taylor and the cases remained 2.50. Fire formed with full strength loads and the cases actually shrunk to 2.48. Is this normally expected? Problem?

Thanks for the expert advise.

You fire formed them and they expanded like a balloon making them shorter.

When you resize them they will get longer.

If your chamber is really huge and your sizing die really tight they will get longer than they were originally when you resize them.
There is another thread with the guy complaining about his sized cases being too long because of this.
I sort of ran on too long but you might read my comments there.

Case stretch and so on..

Thanks for the help. Resized and they stayed the same, loaded and took to the range. did lengthen when shot but only slightly, guess all is well.

Sounds like you have a very good match between the size of your chamber and the size of your sizer die.