Hodgdon 2017 and Hornady app both have loads for it. Dirtyharry might still have these Barnes: https://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/17673386/barnes-348-bullets

Looks like Varget and H4350 are good for both the 200 & 250. There’s also some FTX 200s out there floating around. I have a box of old Winchester 348 loaded rounds that I’d pull apart and sell you the brass, bullets and box if you want them.