I haven't tried resizing 6.5 Creedmoor brass but it should work very well. It is a little shorter in the neck/shoulder junction but I would guess the resizing of the thicker case body would push the shoulder forward a little.

I haven't had any trouble resizing .22-250's to .250 Savage, but if that turns out to be a problem around 15 grains of Unique, with enough uncooked Cream of Wheat on top to fill the case to the base of the neck, plus a "wad" made of paper towel or a medium-sized bore patch, will fireform the .22-250's to your .250 Savage chamber.

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