Action Films Once Used Real Bullets
In today's films, shooting effects are usually achieved with blanks, tiny explosives called "squibs," and if that's too much trouble, a dose of computer magic. In Hollywood's early years, they didn't have access to such fancy tools, so whenever gunfights occur in early movies, there's a good chance that they're really shooting at each other. If you lived near a film set, we're guessing you stayed inside that day.
They did have blanks back then, but that only lets you appear to fire the gun. To simulate a bullet hitting a wall/window/etc. next to an actor, well, they simply had a guy shoot it. If you needed some artillery fire for a war scene, same deal. All of the cannon fire in 1915's The Birth Of A Nation (the classic film that paints the KKK as the good guys, because 1915) is the real thing -- the pyrotechnics to fake it hadn't been invented yet.
Epoch Producing Co.
"I also insist on real racists! My audience demands authenticity!"
Then you have the infamously insane director Cecil B. DeMille (not his only appearance on the list, by the way), who had blanks available to him but thought live ammunition looked more realistic. For the 1915 film The Captive, he wanted a scene wherein some soldiers shoot their way through a door with real bullets, because it would look cool as hell. Then for the next scene, they were to rush inside and continue the shootout with blanks. Want to guess what happened?
Hint: Think Brandon Lee in The Crow.
Yep, somebody forgot to swap out the real bullets and an actor got fucking killed.
In the decades to come, "squibs" to simulate bullet strikes were around but still expensive, and action movies began to run ads boasting that they'd used real bullets, the same way Tom Cruise movies now go on and on about how he does his own stunts. The studios would hire marksmen, and they'd have to carefully plan shots so that actors weren't at risk even from a ricochet.
In William Wellman's 1931 gangster film The Public Enemy, James Cagney (and everyone else on set) swears they shot up this corner a split second after he ducked around it ...
Apparently they really had it out for Cagney.