Huvius I can't advise on the projectiles however that is one sweet looking rifle.

Will the magazine box in this rifle take a 404J or 375H&H length round? I just find it strange that they made a 280Ross and did not open the magazine up to properly accommodate what I think was the norm foe 7mm at the time,160 grain bullets Though as you said the Ross normally ran 140grain bullets but I would have thought that was the military load.

I stand to be corrected on what I have written.