[Alpo]

Safety.

First, yes they had safeties in guns that old.

Revolvers, except for a few European types, don't have safeties. This is a major "look at what that stupid author wrote" laugh causer, to pro-gun people. "Rick Shovel pulled his Smith and Wesson revolver and took the safety off".

Unlike what it shows in the movies, generally a safety prevents the trigger and/or hammer from moving, so pulling the trigger with the safety on would result in nothing. Trigger don't pull. Nothing moves. No sound.

Smith and Wesson, pretty much, only made revolvers back then. They made one little pocket auto, and it didn't sell really well, so they weren't around very long.

The feel. When you pull the trigger on a gun that is ready to fire, you feel the trigger start to move. There is some resistance against your finger, and as you continue pulling the resistance gets greater (you are compressing a spring) until the trigger "breaks" and the hammer falls.

When you pull the trigger of a gun that has the safety on, there is no movement at all. The trigger feels like it is a solid part of the gun, instead of a moveable part. You can pull 'til the veins bulge on your forehead and your nose starts to bleed, and it doesn't move.

There were a few pistols, back then, that had what was called a "hammer-drop safety" (Walther springs immediately to mind). When the gun is cocked, the trigger is to the rear of the trigger guard. If you put the safety on, the trigger is locked in that position, a block moves in front of the firing pin, and the hammer falls, hitting the block so the gun does not fire. As long as the safety is on, the block is there, the gun won't fire, and the trigger is locked to the back of the trigger guard, and will not move. If, however, the hammer was down (the gun was NOT cocked), and you put the safety on, it still moves the block in the way, but now the trigger is disconnected. If you were to pull the trigger, it moves, but the spring pressure you are pushing against is less that what you would find on a ball-point pen. Nothing else will happen. The hammer does not move, the gun won't fire.

That might be an idea. Have him find a Walther - either a PP or PPK, fully loaded and hammer down on a loaded chamber, but the safety on. He picks it up and pull the trigger a time or two, and nothing happens - the trigger kinda swinging freely - and the he looks, sees the safety lever, disengages it and the gun is now good to go, with from seven to nine shots, depending on gun and caliber.