[DBrow]

A prop gun typically has an obstruction in the barrel just in case a live load (not a blank) gets loaded. A bullet won’t make it down the barrel. But...a blank still ejects a lot of hot gas and whatever closed off the blank, so at close range they can be lethal (obviously now).

[jonascord]

Some prop guns have a set screw with a hole drilled through it, tapped into the end of the barrel. This provides enough restriction to work the action on most sub machine guns, and some semi-automatic pistols. (The M-1911 is one that won't cycle, and is replaced with a Llama, which will work with blanks, and looks the same. Something to do with the barrel link.)

Non-auto prop guns, for westerns, like lever actions Winchesters, and Colt .45s do not. And example of this is a John Wayne western where you see a puff of smoke from the breech of a rifle. They use 5-in-1 blanks, load with a flash powder, that gives a nice white flash for the camera.

More than adequate to blow any barrel obstruction into an actor. It's why they are SUPPOSED to have an armorer on set to confirm such things, who hands the gun to the actor just before, and takes it away immediately after the filming.

Would anyone here trust Baldwin with even a rubber gun?