Jalas

As far as I know the 1903 action did not come out in 7X57 though some gunsmiths have re-barreled it to 7X57.

The post 1950 action is a different one & 7X57 as well as the 6.5X54MS were made in that action. The rifle is a bit heavier than the 1903 model.

If you find a Greek military 1903 rifle with a corroded bore it is worth re-barreling to 7X57. But there are a few VERY IMPORTANT things to remember. The action was made for a low pressure round & you should not fire Norma 7X57 in it. Only use US factory loads or 150 gr bullets at about 2400 fps. The second issue is the 1903 rifle's magazine. The rotary magazine has a central spindle that is unique to each cartridge. It will not feed a 7X57 cartridge because the shoulder is different & the base diameter is larger, though the length is adequate. I have seen rifles where a gunsmith has welded a "U" shaped metal piece in the front of the magazine to keep the cartridges aligned in the right direction so that it feeds properly. It would be a tricky job to machine the spindle to accept the 7X57 but a good machinist should be able to do it.