308 won't work. The shoulder is pushed back on the Creed so long bullets can be seated out farther rather than into the case (in a standard short action). That's why it's a different cartridge than the 260 Remington or older 6.5-308 wildcats.
Sorry, Speed3, I don't have. When I chamber something new, I'll rent them with a reamer from 4D.
Standard 308 gauge, IIRC the 6.5CM is based off the 308 case - like my .260 is.
Just for informational purposes, the 6.5 CM case is based off of the .30 TC.
https://en.wikipedia.org/wiki/.30_TC
And the 30TC traces it's lineage back to the 308Win as well.
https://en.wikipedia.org/wiki/6.5mm_Creedmoor
But with the shoulder set-back, yeah a 308 gauge isn't going to work, so I stand corrected.
EABCo shows 6.5CM gauges in stock, $27 (Forster).
https://www.eabco.net/Forster-Headspace-Gauges_p_14570.html