Lazs - thank you for your forbearance!
About single action and double action. I'll reread that long email you sent me, but I can't do it just now as it's on my other system.
Reading this, I've been led to understand that "single action" is like a .357 Magnum revolver - the only gun I've ever "played" with. There was only one thing to do: Pull the trigger. As the trigger was pulled, the hammer would come back and the chamber would revolve to bring the next round into alignment with the barrel. Then the hammer would fall. The only variation would be to manually cock the hammer which would reduce the load on the trigger (and revolve the chamber, bringing the next round into position?) So what's double action? Is that a gun which needs to be primed manually for firing after each shot, hence two actions? Just wondering, because in one of those Clint Eastwood dollars films, he shoots about four of Ramone's men, and they didn't even have time to blink. He could not have done that if having to cock the weapon each time.
That leads on to something else. In some cowboy westerns, I have seen a technique which they referred to as "fanning". All rounds were discharged by the gunman knocking the hammer back with his other hand, presumably while keeping the trigger squeezed. Would this have been a technique to enable rapid fire, overcoming the limitation of having to manually prime the gun for each shot? Would this be necessary with single action weapons? Is this possible only with revolvers? After reading Lazs's explanation about the mechanics of a semi-auto, fanning would not seem to be applicable to that type of gun.