Doug, my advice please go out and buy a MEC reloader. They are simple to operate and from the chamber pressure tables provided by all the powder manufacturers you can pick a low pressure load or you can load black powder. That is after you have your barrels tested by a competant gunsmith that is versed in the ways of "twist" construction!!!
The nice thing about a double is you don't have to do an extensive re-sizing of the shell like you must with a pump or an auto-loader. The double's chambers size the shell for you. On re-loading presses there is a re-conditioning station and that's all you really need for your double.
All the best
