I'm looking for a .280 Ross case.

Might be easy,depending on exactly what you are after.

If what you want is a case that is correctly dimensioned for shooting in a .280 Ross rifle, then a standard ".280 Kynoch" headstamped case should be fairly easy to find in your part of the world. They were fairly popular highland stalking rifles in Scotland at one time.

On the other hand, a case headstamped ".280 , Ross Rifle Company, PQ" is likely gonna be pretty tough, even in eastern Canada where they were made. I have a dozen or so of them around here somewhere in my stuff, but haven't laid eyes on them for at least 15-20 years. Keep intending to go through all my cartridges to find them, but never get around to it now that two cats have taken up residence in my shop. Don't want to leave a lot of stuff laying out at night when I am part way through looking at bits and pieces....

I should have one you can have.