Fire Forming 7mmRem mag to 30-338 Win mag?

[BigBoreGuy]

I just found a nice 40X in 30-338 in local gun shop and bought it. Now I need some brass. It looks to me like maybe I could form fire the 7MMR for it. Is this possible and secondly is it ADVISABLE? If both answers are yes I would welcome any advise on methods and load to do so.

 

[30378]

Yup, it will work just fine. I would full length size the brass in the 30/338 die to size the brass and expand the necks. From there you should be good to go. After the initial firing of the brass then neck size the brass if it is your desire.

 

[M9Powell]

Norma 308 Mag cases are available & identical to 30-338 already.
You can also neck 338 mag cases down without having to fireform.