All these pictures and comments are correct, but I don't know that they answer your question.

The terms "long action" and "short action" refer to the distance the hammer falls once it's been released by the trigger. More specifically, the terms refer to the amount of time it takes for the hammer to fall/for the gun to fire.

I know of three (hand ejector revolver) actions (from the factory) extant within the 20th century. The pre-war "long action"---the post-war "short action"----the action on the single action only K-38 which is shorter yet.

As an aside, we had occasion to measure the "short action" and the "shorter yet" action during the Southeast Bunch gathering in South Carolina today. I had said it was 20% shorter/faster in the other thread----a close, but no cigar answer. Assuming I've understood and done the math correctly (not an assumption you want to bet money on) it's closer to 14%.

Ralph Tremaine