The 348 WCF case is based on the 50-110 WCF case.

50-110 new commercial brass is available,,about $1/piece from Starline,ect.
Actually being able to form the 50 down to a tapered 348 w/o a handful of different dies, a decent size press and a lot of time is another thing. I'm sure it can be done, I've seen some pretty radical case forming done.

My best advise for the OP would be to get into a simple single stage reloading press, set of dies, ect. Load your own to your own specs. It isn't hard to do, you'll know exactly what they are and the equiptment never goes to waste,,there's always another gun begging for ammo.