Hi Lancaster.
I have a Ross M1910 that I shoot regularly. I have purchased resized brass that I believe originally started life as 375 Ruger brass. If memory serves me correctly, resizing is a several step process.
I make my own brass from 300 Win Mag cases. I simply run them through the 280 FL sizing die and trim to length. Even thou the 300 Win Mag is belted, The cartridges feed and chamber without issue. I check all by brass with a sharp scribe inside the case and I haven't had any issues with case separation.
I had found others online who do the same thing without issue. Use your own judgement.
I love the history of the 280 Ross cartridge. I'm able to shoot very accurate open sight groups that chrono 145 grain bullets at just over 3000 fps. Not bad for a cartridge designed in 1905!