6x57 is rather doable. So is the 22x57.

Neck thickness of your brass will be determined by the reamer you will be using. I would neck turn the brass 0.003 to 0.004" prior to necking down though. Lot nicer to start off with coencentric necks than trying to fix after that fact.

Why not just run a 22/6mm or 22/6mm AI? 3900+ with 75 gr bullets is just a touch fun on prairie dogs.

If I have a plethora of x57 brass, I would HIGHLY consider a 6.5x57.