I had a problem with measuring strike depths.
The thickness of the brass that forms the rim varies also.
During the cupping and heading process, brass is stretched and shaped
and the machine tolerances along with the properties of the brass being used
can produces rims/heads/case walls that are not uniform in thickness.
I've had pin strikes that were barely deep enough to be measurable.
Cartridges did not fire. Disassembled the cartridge and there was no cup in the rim.
No hollow for primer to fill, solid brass from sidewall to head.
Another of those variables that affect results.