The 6.5x55 offers short action performance in a long action. It was a remarkably innovative cartridge when it came out (superior to the .30-03/06 almost a decade earlier) but suffers from all the problems of cartridges designed for machine gun use, plus being designed for an awkward intermediate action.
Just get the Creedmoor and have the superior gun.
Never heard of it being designed for machinegun use.
In that era all military cartridges had unneeded taper and shoulder slope added because it was believed to be required for reliable machinegun feeding. Since neither brass stretch nor actual accuracy was of military concern, it was viewed as a reasonable trade-off. For a hunter, it's a horrible trade-off.
We now know that case geometry is completely unnecessary for machine guns as well (consider the .277 Sig Fury) but at the time that was what they thought.
