I read in one of the threads on this forum where someone was resizing 7mag brass into 257 weatherby mag . Is this possible? If so how many steps and what are they. Thanks. I read this forum daily but this is my first post.
Second, I may be the one that started the thread you are referring to. Yes it is possible, and yes I am doing it. Lube the case up with Imperial Wax and one it throught the .257 Weatherby Die adjusted for a "crush" fit and that is all there is to it. It will be slightly shorter than actual .257 Roy brass, but after a couple of firings you won't be able to tell, and you get the added bonus of probably never having to trim the cases back to spec.
Here is a link to the thread I started, and an associated group I fired with said brass:
Be sure to use NEW brass when doing this. I found out by experience that even once fired doesn't get the job done very easy. You'll have quite a bit of variance in shoulder dimensions etc.
Use the new brass and it works good!!