This is an Auto-Revolver concept that I proposed to [link]
Nothing spectacular art wise but it gets the point across.
It is a gas operated revolver, using gas to cycle the cylinder and also re-cock the hammer so that you do not have to pull back a full weight. Two version:
The top has a hammer like all conventional revolvers, but uses gas to cycle the cylinder and to reset the hammer to full cock.
The bottom has a bolt which would allow for removal of the Main Spring that is used to force the hammer down on the primer of a projectile. Makes the revolver look more like a Semi-Auto Self-Loading Pistol with a cylinder, which coincidentally is just like the 10mm pistol from Fallout 1: [link]
(You have to look very closely).
These are designed for use in the FO:E universe, but feel free to use them (not that anyone probably will) elsewhere.