6mm shooting Federal factory?

[gorilla10]

I'm having a problem, I have a model 4 Rem 6mm. I bought 2 boxes of Federal ammo. For some reason, there's way too much pressure? The ejector is breaking off a small piece of the base, the spent cartridge remains in the chamber, the next problem is the primer shows cratering/primer flow! Has anyone ever experienced this, if so help.
I haven't had this problem with Rem. ammo? But I prefer Federal.