As Jim states, that Mk 1 frame was designed around the .30-06 load of the time, plus is was designed to be as light as possible, and I would also say that a 300 Win Mag would be too hot for it. Back then, Springfield, like several other manufacturers, didn't use Browning's philosophy of designing a gun that would work, then double the specs. If I recall correctly, nickel steel had just came on the market, for use in firearms, when Winchester started the manufacture of the Model 12, in 1912. It wasn't until later, during or after WWI, that high strength alloy steel, such as 4140 and 4150, came onto the scene, from Germany. So both metals were after 1903.