I can add little to what has been said. However, to re-enforce some of the other comments: it is no great trick to cast bullets using a wood fire. As many here have said, wood fired heat (I haven't used "buffalo chips") is more than adequate. My local club has an indoor range. I have often helped clean the range of lead. We smelted it in a very large iron pot suspended over a fifty gallon barrel full of burning wood. This worked as well as my modern propane fired turkey cooker (it was larger, tho' by far). We only clean the range when is about to collapse the floor and we are talking hundreds of pounds of lead.
I grew up on a farm where a wood fired range was still in use in the kitchen. I have cast bullets on the range using a Lyman iron pot and fire ring to suspend the pot over the fire. It is pretty easy to regulate the fire in an old range - we often used corn cobs for fuel and the number of cobs were easily translated to the numbers on your modern range heat control knob...
Probably the most "businesslike" individual on the original Buffalo range was Frank Mayer. Here is an excerpt from his book, Buffalo Harvest...
http://www.pbs.org/weta/thewest/reso...ve/buffalo.htm
Frank kept meticulous records, records that the yet to be invented IRS would have been proud of. I don't know if he mentions it in this account, but I have his book and he ordered bullets, swaged and paper patched, from Sharps. As I remember, he used 16-1 lead-tin for his bullets (he left a very detailed account of all things involved in his ten years chasing Buffalo). What is more, he was a real "rifle crank" and continued to be interested in serious rifles until old age. He lived until the 1950's, I believe. I would have liked to have known him.
Dale53