To answer your First question: Anything is possible with black powder being involved. At the very least it would just burn.
To answer your Second question: I whole heartily agree with articap's reply. In reality to dig a revolver up out for the ash and coals of a burnt down building. Repair it, and have it shoot accurately again is not likely to happen. Well maybe in the movies it can. For instance in The Outlaw Josey Wales movie. Mr Wales salvaged not only his six gun but also its leather holster from the ash & coals of a burnt out building. But that's a movie. Certainly not reality.
Watch it!!! their both out to get us.