How do movie guns work? I mean they fire blanks. They cycle properly and they have muzzle flashes. In the army when we are training with blanks we have to use a blank fire adapter. It is something that screws into the end of the barrel and is quite obvious. The way semi-auto and automatic weapons work is by using the gas produced from firing the round to cycle the bolt and eject the round. The gas is redirected from the barrel through tubes. When you use blanks there is less gas produced and there is no pressure do to there being no bullet in the barrel. Without a BFA the weapon would fire one round and then stop. There are obviously no BFAs on movie guns. If they have an internal part that blocks off the barrel how do they also have the proper muzzle flash?
Not an expert by any means, but I heard from an FX guy that in a lot of cases they add the muzzle flash in post.
As it happens, we modified a Beretta 92FS for use in a film. Yep, surgery on a brand-new 20-year-old Beretta.
I’ve posted what we did elsewhere a couple/few times already, so I’ll be brief. In the case of something like an M-16 there is a ‘hollywood style’ blank firing adapter (BFA) that is a plug with a hole in it that fits between the barrel and the flash hider. For the Beretta we threaded the breech and put in a set scre and then drilled a hole in it. An M-16 will cycle with GI blank ammunition using the BFA. The Beretta needed some surgery on its locking lugs. Needless to say, we tested it thoroughly before letting an actor touch it.
The full-power Stembridge blanks we used look impressive. See this clip at about 00:34. We got some other footage where I was taping from a frontal position. Nice big flame (and concussion). In the clip I’ve linked you can also see a 9mm Sig of some sort being fired. We were using live ammunition with that one since we didn’t want to do the tapping and the drilling and the grinding on it. Note how wimpy the muzzle blast is compared to the blank-firing one. The SAR-8 is also firing live, and there’s no flash at all.
If you look carefully you can see these types of modifications in a lot of films, particularly on gas-piston operated rifles. (The one that comes to mind is the FN-FAL that Pacino uses in the downtown Los Angeles shootout scene in Heat.)
Yeah, and when they do this you can definitely tell; the flash and reflections on background look very flat and unrealistic. Most feature films will use real blanks. The muzzle blast, however, is almost always added in post-production by the foley artists using a combination of sounds that are not derived from gunshots. Real gun reports sound like kind of a flat bang, not the resonating boom one is accustomed to in movies and television.
Stranger
Interesting. Here in the UK some guys have just been jailed for running a weapons factory converting replicas to firing weapons. They purchased 90 MAC-10 replicas legally by claiming that they were purchasing them for a James Bond film. Link here
Si
Seems to me changing out the springs to a lightweight version would get the action to cycle with blanks. There’s maybe more gunsmithing to it than that, but as I understand the issue is that with no heavy bullet, your .45 blank isn’t kicking enough to rack the slide. But maybe it kicks as hard as a .22 so you use .22 strength springs, a lighter slide, etc. Just a guess.
The problem with that is that the cycling of the action has to carry enough energy to chamber the next round from the magazine as well. Using a weak spring and a very light slide might allow the slide to be kicked back to full extension, but it would almost certainly jam every time it hit the next cartridge. After all, if light springs and slides would work to cycle a .45, you would see them on real guns. The slide on a .45-caliber pistol is heavy because it needs that inertia to push the next round out of the magazine and into the chamber.
Bulleted blanks have been used, in scenes where there is little danger of anyone getting hit.
I attended a lecture once by a man who has worked as an armourer on many movies with firearms use. In Where Eagles Dare he was the gunner firing the tripod-mounted machine-gun on the stairs inside the castle.
Lying in front of the gun, as a corpse, was an old extra called Paddy, now long gone. Paddy’s arse was peppered with splinters from the wooden bullets (which break up on emerging) and they spent some time with a pair of pliers pulling them out.
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Quote:
Originally Posted by OompaLoompa
Seems to me changing out the springs to a lightweight version would get the action to cycle with blanks. There’s maybe more gunsmithing to it than that, but as I understand the issue is that with no heavy bullet, your .45 blank isn’t kicking enough to rack the slide. But maybe it kicks as hard as a .22 so you use .22 strength springs, a lighter slide, etc. Just a guess.
The problem with that is that the cycling of the action has to carry enough energy to chamber the next round from the magazine as well. Using a weak spring and a very light slide might allow the slide to be kicked back to full extension, but it would almost certainly jam every time it hit the next cartridge. After all, if light springs and slides would work to cycle a .45, you would see them on real guns. The slide on a .45-caliber pistol is heavy because it needs that inertia to push the next round out of the magazine and into the chamber.
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Naw. The force required to flick a new round out of the magazine and up the ramp is miniscule (you’d bruise your fingernail doing it) to compared to the backwards force of the exploding round, and handguns are designed to safely contain that for 5000 times or so. The slide and spring are first designed to keep from going in the user’s eye, after all. The inertia of the slide, and then the weight of the gun, and then your hand and elbow, etc, spreads out the force. The spring and slide return some portion of the energy.
I might’ve overstated the importance of mass because with today’s materials you can probably make a gun so light nobody wants to shoot it. I was also assuming custom feed ramps and magazines designed for blanks. Loach would know better than I about how many rounds before they shoot loose or how light is too light for a .45.
Oh, easily more than 5000. I’ve probably put almost that many rounds through my Kimber Custom II, and it hasn’t shown even the slightest sign of loosening up yet. I’ll probably replace the recoil spring soon, but other than that the only maintenance I do is periodic cleaning.
You’re right, though; I wasn’t really thinking about the safe containment of recoil force. The obvious fact that a light slide would also drastically increase felt recoil also slipped my mind. :smack:
In any case, though, the recoil from a blank is probably not even going to carry as much energy as a .22 bullet, which is very small, but still has a heck of a lot of mass compared to the expanding gas from a blank. I still have doubts that a spring and slide light enough to be cycled by an unimpinged blank would be able to function reliably, though I suppose a looser magazine might help.
I don’t know if anyone still does it this way, but an in-depth article I read years ago (in Cinefex magazine) about the making of the film Aliens explained:
Because the ‘futuristic’ pulse-rifles in the film were actually real Thompson submachine guns just redressed, they used what they called ‘wooden blanks’. They were cartridges with a balsa wood projectile. The F/X guy said that when they tell actors that they kinda freak thinking the guns would be shooting splinters! But he said the balsa wood just vaporizes, and they provide enough back pressure for the guns to fire full-auto normally. Plus they still provide a realistic muzzle flash.
If you watch some scenes in the film closely you can actually see the spent brass cartridges flying out of the guns. For fanboys this is a mistake because the weapons were supposed to be using futuristic ‘caseless’ ammunition. The flamethrowers in the film were also real honest to god flamethrowers.
Well I got curious again and used google instead of wasting my time just thinking about it. Turns out they do indeed cycle, in semi and full auto. Purpose-built just as a blank gun of course, hence all the confusion comparing them to a real gun firing blanks. Here’s a sample site that sells them:
http://www.stage-props-blank-guns.com/stage_movie_props/catalog/MODERN-BLANK-GUNS-p-1-c-166.html
Here’s a youtube of a guy firing his full-auto blank gun, interestingly the flash seems to come from the ejection port rather than the muzzle. I’m sure you could achieve plenty of flash with an unblocked muzzle and the right pyrotechnic blend though.
I’d imagine the BFA mentioned in the OP simply “chokes” the end of the barrel to cause the expanding gas to kick back harder than it would otherwise.
IANAGE, but I think that handgun slides are recoil operated and don’t need a blank adapter. Only when you get to rifles, like the M-16, which are gas operated, do you need the blank adapter.
Also, IIRC, the problem with handguns is not the lack of force to rack the slide, but controlling the excessive force. A .22 handgun might operate on a straight blowback, but a .45 needs a system of controlling the recoil to prevent damage to the slide.
Nope. See my post (#3). If you shoot a blank in an open barrel there’s no recoil because the gasses aren’t pushing against anything. That’s why we threaded the breech and installed a set screw with a hole in it – to give the gasses something to push against, generating recoil, and to let the excess gasses out of the end of the barrel.
We assumed that’s all we’d have to do, since that’s how it works in an AR-15. But it didn’t. We tried lighter springs. That didn’t work. We had to grind some metal to get it to cycle.