Clayton my good man, I have had exactly those thoughts. Straight-case that 7.62x25 and get yourself something in the power range of the old 401WSL and go huntin'.
However, I don't know if you can fire-form something like that, although I don't know why not. Heck, the 06 case has been blown out to a 444 caliber so why not the 7.62 to .401??. You have to expand the neck to take a 401WSL bullet and load it over a light charge and that should expand the case without blowing it.
If you just need .401WSL brass, I'm sure that someone like Starline probably already produces that case. HTH. Mikey.