This is a link to the a thread on the AR forum that I have contributed to, but I thought that folks on this forum who are interested in building doubles, would find this both interesting and useful. I am sure most of you are aware of Vic Venters' book "Gun craft". There are couple chapters in it that are particularly useful to double rifle builders - especially the chapter on "Jointing and The Circle". All builders should read it.

http://forums.accuratereloading.com/eve/forums/a/tpc/f/760101804/m/5861016271

Ellis