A pretty little double action gun is the 1877 Colt Thunderer .41LC. The lightning version was .38LC. They're nice in the hand and accurate too, but the damn thing was highly sensitive and was as undependable as a Yugo. It's hard to find one that functions 100%.
Both Billy The Kid and Wes Hardin both carried them. Fix the internals and you'll have a great gun to put out. Mine's in perfect working order, but I'm afraid to breath on it for fear of something breaking. Got it many years ago from someone in LE who it was past down to from a great grandfather with it's original unsigned scabbard holster.
I picked up an exc. old flap holster that was originally gotten through mail order like the example in Guns Of The Gunfighters. Hope you like looking at it.
Sorry for blurred photo. Stampings show 5,38,41,4 1/2. It fits Thund & Lightning