I saw an M1917 or a P-14 at a gun show in 458 Lott or it may have been 458 Win Mag but I think it 458 Lott. I guess the 303 bolt face lends itself better to magnum belted cartridges but I'm not sure which bolt this one had. I did find a US M1917 (or was it the 1903?) armorer's manual on the internet which I think included barrel replacement. Not that it's much different from any other though. The receiver is big but I keep reading all these things about how brittle they are.The British used only the Winchester P-14's as sniper rifles, because they found them the highest quality and the most accurate.