Actually the 338 am is not a shortened 408,but based on the full length blown out 408 ct round. This weekend showed that 3500 fps is not quite obtainable,high 3400's was.This was with 150 grns of powder(151 peirced the primer)
If you would like a water capacity of that case holler as I have quite a few down in the basement,I also have the standard cheytec case and could provide that as well if you wished