The only gun that will look like the Ruger Blawk and not be a single action would maybe be the Colt Lightening Clone by Uberti. That is the only look-a-like cowboy style (Ruger Blackhawk) in double action. Colt originally made them back in the 1870's I believe.
However, you can't shoot the heavy load rounds that you could with the Ruger BH. I may be wrong, but I don't know if Uberti still makes them or if they are double or single actions.
Check this out:
http://www.answers.com/topic/colt-lightningPropably doesn't help you much, but it can shed a little light on your question that no one wanted to answer.
