I'm not familiar with the 6.5 creedmore. Can you give a little background on it? What is the parent that has been necked down to 6.5 Are the shells available over the counter or do they have to be hand made? Thanks for the info.
It does not have a parent case, it was created by Hornady.
It is the baby of across-the-course shooters who are competing against .308s and .300 Win Mags. This cartridge fits in a short action (or AR-10 action) but has a better trajectory and less wind-drift than a .300 Win Mag.
Hornady sells ammo. Not sure who else. If you're really using the cartridge to its capacity (600+ yards), you'll want to handload. It's similar-ish to the .260 Remington.