Here is Hodgdon's website I refer to a lot. Select 30-40 Krag for the cartridge and you're on your way.

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Have you checked out Black Hills for loaded ammo?

You should get a few reloading books and study up on reloading if you are going to try that. Wouldn't hurt to talk to some buddies that are competent/safe reloaders. Reloading books are available from the following:
    Lee
    Hornady
    Speer
    Sierra
    and many more

Be safe.