The exile: On Gunboards and various websites I've read where the 8**,*** (800,000 +), a very specific serial number was the last rifle which had the Old, unsafe type of steel metallurgy process. My impression is that any 1903 rifles After that serial number (-if I knew the exact number I would say so-) should be safe, as long as headspace is within limits. *The M1917 rifle ( all had aperture sights): reportedly a serious fraction of US troops in WW1 used the British rifle chambered for our ".30 cal US govt." cartridge. But when returning home, former US troops usually preferred the US-made 1903 rifle, having its Mauser-like appearance (and Mauser technology).