In addition to other "pros" of the 6.5 Creedmore already mentioned, it also has a reputation for accuracy, and being easy to develop good loads for.
FWIW the Creedmore case is nearly identical to the efficient 250-3000 Ackley Improved, which has a reputation for superb accuracy (Sierra tests all their 25-cal bullets from a 250 AI barrel.) There are chaps who say they simply run new Creedmore cases though a 250 AI full length or Type 'S' bushing die, load 25-cal bullets, and go shooting. I still fireform my 250 AI cases "bulletless"(from premium 22-250 brass) but the Creedmore case offers another way to make the 250 AI.
Last edited by brians356; 08/02/16.