257 STW back to 7mm STW

Long story short, I'm going through all dads old STW stuff. I've found some 50 or so virgin 257 STW cases dad made from RP 7mm STW cases. It looks like he *may* have turned the necks on them after the fact as they are shiny around the neck. However, I know he never discussed t and certainly didn't have a neck reamer in his equipment. My brother got the 257 STW but doesn't reload or really even shoot. I've got maybe 150 loaded rounds of 257 STW to give him.

I guess my question is, can I just run the virgin formed 257 STW brass through the 7 STW sizer die and be GTG or am I gonna cause issues with split necks or have short Trim to lengths due to down sizing and resizing back to 7mm? The 257 STW brass has obviously been sized and trimmed.

Also, I have 8mm Remington brass 1X as far as I know. Am I able to just run this through the sizer for the 7mm or are there other process to do?

How often (when) and what method should I be annealing this brass for longest life possible?

Never done the wildcat thing.

Not sure about the 257 STW cases. I do the 8mm Remmy. Run them thru the sizer, trim if needed and fireform with a reduced load. I do outside neck trim after fireforming.

You can anneal after every firing if you want. The right temp is the important part of the equation. I anneal every 4 or 5 firings.