This project sounds like a lot of fun. Mauser 98 actions were first made for military rifles, especially the ones that shoot 8mm bullets. But a lot of them were changed on so you need to look at the marks on them like the proof marks and the serial number style to figure out where they came from and how old they are.
If you want to make your Mauser 98 action shoot 7x57 bullets that is a common thing to do. The Mauser 98 action and the 7x57 bullet are a match.. It is not a simple job that you can do by yourself. You will need to get a barrel and make sure the headspacing is right. You might also need to make some changes to how the bulletsre fed into the gun.
If the Mauser 98 action is, in shape it is a strong and reliable gun that is worth building on. The Mauser 98 action is a platform to start with.
