This is patently false. Thompson center started with the .300 Savage case. It was well discussed and documented at the time when TC was working it up 10yrs ago, and those of us following along bemoaned the lie which was its performance "Improvement" over existing cartridges... Run a .30-06 or .308win at 60kpsi and you'll outperform the TC, with the same bolt thrust and chamber pressure... lots of us were looking around and scratching our heads, asking, "why?"

This too is false. Not all short action cartridges have the same head diameter. There are 3 standard short action bolt face diameters, and a handful of specialty diameters.

But in the case of the 6.5 creedmoor, indeed, the lineage as I described above DOES root back to the Savage case, just the same as the 22-250.

A rose by any other name... the moral of the story is the creedmoor case is a tiny little thing, more comparable to a varmint cartridge than a big game cartridge. As such, those 140grn pills are running on a V6 engine of a powder charge weight, and are really only so capable.