The 280 Ross is a fairly interesting cartridge. Some 25 years ago,I read about using 300 WM for both the 280 Ross and the 30 Newton.

I finally got a Ross 1910 which came with 50 cases formed from 348 Win (must have used a hydraulic press as the head is much larger). Unfortunately the cases had not been annealed and I lost some 20 cases with neck splits shooting this cartridge.

Cases can also be formed from 30 Newton which was available from Jamison.

However, the 300 WM are more readily available and seem to work very well for both 280 Ross and 30 Newton.