Just finished having a built up 98 Mauser in 256 Newton made. The only difficult areas have to do with cartridges. Making brass can be a chore. Also, loading data is dated. Wonder how long before somebody re-introduces the Newton? We are gradually catching up with 1914.
The most recent loading data that I recall seeing for the 256 Newton is the data that Ken Waters put together for the May 1987 edition of Handloader that is in his Pet Loads books.
I'd suggest starting with maximum recommended loads for the 6.5x55 and work toward the minimum recommended loads for the 6.5-06, since the 256 Newton's case capacity falls somewhere between those two well documented cartridges.
