I recently located 2 NOS M1903 barrels made by Springffield Armory and High Standard, both dated 1944 and quite expensive, but the real thing.
As pointed out, the more common 03A3 barrels will work on a M1903 as the threads are identical, but you must turn down the barrel OD over the chamber in order to install the rear sight sleeve. You also need to replace the 03A3 front sight band/mount with one made for the M1903. It's kind of a PITA to do this right. The rear sight bases are quite fragile and care must be taken when driving them on so that they are not deformed in the process.
As pointed out, the more common 03A3 barrels will work on a M1903 as the threads are identical, but you must turn down the barrel OD over the chamber in order to install the rear sight sleeve. You also need to replace the 03A3 front sight band/mount with one made for the M1903. It's kind of a PITA to do this right. The rear sight bases are quite fragile and care must be taken when driving them on so that they are not deformed in the process.




















































