re:
May be just a shot in the dark...but the Virginian Dragoon revolvers had a
"manual safety" of sorts that under the right circumstances could have gone awry and caused a failure to fire. I don't know if this feature was intentional, or if that's just the way it worked out...but it was actually pretty neat.
On these revolvers that I've handled, you could place the hammer in the half-cock position...push the cylinder pin's release/takedown pin...push the cylinder pin rearward...and it would lock the hammer. Then, drawing the hammer back just a bit, and pushing in on the release pin would snap the pin forward again and allow the gun to fire. If something is worn or out of whack in that area, it's possible that the cylinder pin is changing positions under recoil...moving forward under inertia, and maybe rebounding rearward...not far enough to lock the hammer...but enough to interfere with the hammer falling with full energy on the next shot.
If your revolver misfires immediately after firing a round...then fires on the next try...then misfires, etc...mark the cylinder pin and look at it after each round to see if it's moved rearward...and look into the frame, low on the hammer to see if any of the pin is protruding.