I wonder if you know the cause of the .308 separation?
I have had case separation with rifle rounds on several occasions. This is a 308 Winchester case. It is not as exciting as a split base.
The 9mm cases with the band inside do have less powder capacity. I filled a standard case and a case with a band with powder and then weighed both amounts of powder. I don't remember the exact numbers, but you can easily do it yourself.