Home Forums Reloading Big Game Rifles 350 RM from 458 WM

Imperial sizing die wax and three steps to get from 458 Winchester Magnum to 350 Remington Magnum. Has anyone done that? It would cost over a $100 bill to get 50 cases in the Nosler brand. Remington was not in stock, seasonal only. Of course the Remington is way cheaper. I have paid for, unfired brass in 458 Win Mag, bought right in the past. Thus the idea of forming to my needs. I realize there is a process. A lot of trimming for one thing and fire forming on the end to get this stuff true. I think I will use my Corbin press for its precision alignment. TIA Rusty

Wouldn't 338 Win brass be easier to expand up?

Many years ago I did it wirh 7 Rem Mag cases but I don’t remember what, if any, intermediate steps it took.

I already OWN the 458 cases! Sorry to yell but no extra money spent is a good thing as I already bought the rifle, dies, but have the bullets, powder, and Primers. Rusty

Did you need to ream/turn the necks*** since the material came from down the body of the 458 cases?

***Not just for overall thickness, but to eliminate taper in the thickness from mouth to shoulder.

Form and trim dies are going to wreck over $100...if you haven't done so already. Using them will help eliminate case loss, as they form in steps.




And the anneal afterwards, to eliminate splits.

Going down with basic brass is a serious PIA; be prepared to lose some cases and have some wrinkles, real and perceived.

True, the case loss. I just don't feel like paying over $50 for only 25 cases. And even then not primed. Perhaps I'll keep up with the classifieds in a few places. If they are cheap enough I can afford some shipping. Rusty