Only the spent primer would have the stamp on it. It’s easy to pop those out and dispose of. If I were a bad guy, I’d just go to a range and collect a bunch of empty casings and toss them around the crime scene.
Ah. Some “microstamping” laws require that the bolt face apply some sort of mark or stamp. If it’s on the firing pin, it will be difficult to get a half million unique codes in such a small space.