Do you speak Russian, or do you need them in translation?

This site: http://eudocs.lib.byu.edu/index.php/History_of_Russia:_Primary_Documents

has a lot primary source on Russian History, but most of them are in Russian. Let me know if you need specifically English-language (or any other language) translations and I'll see what I can do. Some of these documents use pre-revolutionary orthography for Russian, so modern machine translation software is likely to be worse than useless.

There are English translations available. Just off the top of my head, John Fennell did a couple of translations of Andrei Kurbsky's letters to Ivan IV, for example: John Fennell, ed. The correspondence between Prince A. M. Kurbsky and Tsar Ivan the The Terrible of Russia, 1564-1579, Cambridge UK, 1955; John Fennell, ed., Prince A. M. Kurbski's History of Ivan the IV, Cambridge, UK, 1965. You might also want to check out Sigismund von Herberstein's (SJ) Rerum Moscoviticarum Comentarii, available here.