I would second the advice on bill Brockway’s instruction on browning . its not to complicated and gives a reasonable result
Here is a photo of one such barrel I did using his method
The right barrel in this photo , had yet to be carded
here is another such barrel that was of much lower quality then the above barrel . same process was used but i used a log wood bath after boiling . sorry its not a real good photo .
Now where things get real tricky is when you get down to trying to reproduce an original factory finish . Each manufacture had their own process that resulted in slight differences in the finish
Some of these processes as well as a lot of other good information can be found here
http://www.damascus-barrels.com/index.html Now another very good process with full step by step instruction .
http://docs.google.com/Doc?id=dfg2hmx7_194gwgwmqdh
Here is another very good link that will give you even more information as well as a deeper base of study . it contains a wealth if info as well as a couple diffrent methods of restoration
https://docs.google.com/View?docid=dfg2hmx7_186fpmvhzsb