Movie machineguns and blanks

Maybe some of you who are really into the making of movies can explain something I've always wondered about:

You see in a movie someone blasting away with an automatic weapon with the muzzle blast flashing and maybe even the shell casings being spit out of the breech. How is that done?

My only experience with blank ammunition was with the semi-automatic gas-operated M-1 rifle back in Army basic training in '61. In normal conditions when firing live ammo, the gas generated by the bullet being fired is routed through the rifle to blow back the bolt to allow the ejection of the shell; then the spring-loaded bolt snaps forward, pushing another bullet from the clip into the chamber. As a result, one can fire an 8-round clip of live ammo just as fast as one can pull the trigger.

However, we occasionally would use blanks in attacker-agressor training scenarios. Those blank cartridges did not include the metal slug of a real bullet, of course, and apparently contained a smaller charge of gunpowder, because when a blank was fired from an M-1, the bolt would blow back to eject the casing, but lacking the volume and momentum of gas from firing a real bullet, the bolt would then lock in an open position and had to be released manually to load the next bullet. The result is that a semi-automatic rifle could fire blanks no faster than a bolt-action .22.

And if that was happening with an M-1, then firing blanks would be virtually impossible via a machingun in that the whole automatic rapid fire would be negated.

My guess is that there's no such thing as blanks that can be fired automatically from an automatic weapon and that the automatic weapons seen firing on screen are toy-like props with a some built-in friction device that shoots sparks out of the muzzle simulating machinegun fire like the toy guns we used have when I was a kid. That, however, would not explain the ejection of a steady stream of casings that we sometimes see on screen.

Does anyone have any insight into how Hollywood accomplishes that illusion, which predates computerized special effects?

If I'm right about there not being blanks capable of duplicating automatic firing, then that knocks a big hole in the plot of films like Die Hard 2 (I think that's the one) in which the rogue squad of soldiers are supposely firing blanks from their machineguns to fool Bruce Willis and the other good guys.

In Come and See (http://www.imdb.com/title/tt0091251/)it's not an illusion, live ammunition was used.

According to IMDB, actor Aleksei Kravchenko describes bullets passing some ten centimeters above his head.

I thought it was odd that the information is in area labeled Fun Stuff.

Live bullets whizzing pass a teenager's head isn't what I would describe as fun.

I wouldn't recommend this film to any animal lovers.

Live ammo has been used in Hollywood for years. Cagney told a story about filming Angels with Dirty Faces when his gangster character is trapped in an empty industrial building and is shooting it out with the cops below. He said they were using real tommy guns and real ammo to shoot out glass windows in the building. According to Cagney, the director told him to raise his head within a certain space at the start of the scene and a marksman would shoot out the window. The cameras began rolling and Cagney lifted his head as directed into the proper area but then immediately ducked back and to one side. He said one of the bullets ricocheted off the metal window frame right through the space where his head was to have been. If you know where to look in the movie you can see the point where he lifts his head in one direction but immediately moves it to one side.

I once saw a film clip featuring the guy who played the squad's lieutenant in the old Combat! TV series (Rick something--I never can remember his name). He said at the start of the series one of the props they had was a tommy gun, which the prop-man offered to Rick. But, the guy said, Vic Morrow the start of the series thought a tommy gun was really cool and he wanted to carry it. As I recall, the actor playing the lieutenant had been in military service where Morrow had not and therefore knew that the tommy gun is a surpisingly heavy weapon to help hold it on target against its tendency to kick up when firing automatically. Even the non-firing version cut from solid wood that Morrow was to carry in most scenes was extremely heavy, the actor said. And soon Morrow is grousing about having to carry this heavy weapon, especially in scenes requiring him to run or crawl. Meanwhile, the guy playing the lieutenant opted for a prop of the M-1 carbine, which was one of the lightest US rifle used in World War II. I've heard my dad and others say the carbine was practically useless in combat because it didn't have the knock-down power of an M-1 rifle or even the .45 pistol, so that sometimes the enemy would still be advancing toward you even as you kept shooting him. Not what one would want in combat, but exactly the right lightweight arms for a TV prop.

That said, I'm surprised to hear people are still using live amo in modern films. I figured maybe they had some props that would realsiticly simulate automatic fire from a machine gun