A friend of mine on another forum posted this.

I recently came into a very nice 1871 Mauser, NOT a 71/84. It is in very nice shape with one caveat that is a biggie! I don't have a bolt. I am hoping someone here either has an extra or knows where one is available. Even bolt parts would help. Thank you for your time.

He is in the US and I would be very happy to facilitate a communication with him if there is a bolt to be had.