Wow, that is some loose neck. What is the outside diameter after you seat a bullet in the sized case. Even with the bullet in it you are probably WAY good to go. You are probably going to end up having to anneal those brass every 3 or 4 firings or the necks will split. I have never had that much neck clearance on any gun. Usually .005 or 6 from seated with a bullet would be max.You guys are super helpful. Here's what I have:
Outside diameter after sizing: 0.306-0.308 (slight variance)
Outside diameter after firing: 0.323-0.325
Outside diameter with bullet seated: 0.308-0.309
By my math, clearance is atleast 0.015"-0.017"
Just occured to me after I thought bout it a bit; Is the gun by any chance a military surplus version becasue if it is then the neck size makes perfect sense. Military chambers were made intentionally loose so all ammo fit, dirt didn't stop you from shooting and they never figured on reusing the brass anyhow.