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It's generally frowned upon to fire any kind of gun in public places in the UK, even if it's a blank. The radius of frowning generally correlates with the loudness of the bang.

However, as far as I am aware, there is no law against a car backfiring from time to time.

I would derive considerable impish pleasure from having a small button on the dashboard which, when pressed, would activate the engine mismanagement system and produce a hearty backfire.

Were I more familiar with guns, I might also opt to have my exhaust tuned, so that the backfire would resemble more closely the sound of my favourite gun.

Supermarket carparks, long dull traffic cues, slightly wobbly pensioner cyclists - the opportunities are unlimitless.

MaxwellBuchanan, Oct 20 2012

Uncle Joe's "Little Kate" http://en.m.wikiped...sha_rocket_launcher
Something of a limited repertoire … [8th of 7, Oct 21 2012]

Best gun sound in a movie http://www.youtube....watch?v=_XuPHlX0Di4
Fast forward to 1:35 [doctorremulac3, Oct 21 2012]

Cartoon Physics http://en.m.wikiped...n_physics#section_3
Some aspects are very worrying … [8th of 7, Oct 22 2012]


       This is already WKTE, although not for your intended purposes. It's called (amongst many, many other names) an ignition retarder, and it's used in race cars to keep the turbocharger spooled up whilst downshifting. It does exactly what it says on the box, preventing the ignition of a sparkplug during the moment of shifting, which dumps unburned fuel into the hot exhaust manifold where it then ignites, powering the turbo and creating a terrific bang (or, more usually, three or four in rapid sequence).   

       The ignition retarders on modern race cars are tied into the electronic timing of the engine, but I'm led to believe that the earliest ones were button-pushers. They're illegal on street cars most everywhere, for reasons that are obvious to most sensible folks.   

       I'm not sure if you could tune it to accurately reproduce the sound of a firearm, excepting possibly a long-barrelled shotgun loading cheap practice rounds.
Alterother, Oct 20 2012

       This I want very much. Illegal is a relative term.   

       So, if I underhend correctly, all that's needed is a switch which would cut the ignition to a single sparkplug for one cycle? Would there be any adverse effects on a 3.8l V8?
MaxwellBuchanan, Oct 20 2012

       If you paired it with a cut-out gate (also not street-legal, but fairly common in hardcore street racing and off-road circles), you could actually have rapid-fire bursts of flame emerging from beneath your car.
Alterother, Oct 20 2012

       // all that's needed is a switch which would cut the ignition to a single sparkplug for one cycle? //   


       // Would there be any adverse effects on a 3.8l V8? //   

       Not unless you lay on the thing. Using it once in a while will ensue in hilarity with negligible mechanical consequences; using it once or twice per day will cause some carbon build-up that will eventually require cleaning; using it ten or twelve times in a minute will have your manifold glowing cherry, and doing that every minute for half an hour straight will result in fire, explosion, mechanical siezure, or any combination of the above.
Alterother, Oct 20 2012

       //fire, explosion, mechanical siezure, or any combination of the above.//   

       I think that's a small risk.
MaxwellBuchanan, Oct 20 2012

       I would tend to agree. Pull out of the garage before you test it.
Alterother, Oct 20 2012

       //Were I more familiar with guns, I might also opt to have my exhaust tuned, so that the backfire would resemble more closely the sound of my favourite gun.//   

       Colorful life that I've lived, I've heard the sound of gunfire in the streets on a couple of occasions. Rule of thumb: If it sounds impressive, it's probably not a gun. Gunfire is very distinctive, making a "pop pop" sound verses backfires which are a very loud "BOOM!". Of course I'm talking typical handgun ammo like 9mm or 40cal, .38s that sort of thing. Never heard a large caliber rifle fired on the street, only handguns, but rifles also don't go "boom" so much as make a high pitched report that sounds like, well, a rifle. Loud, but not low pitched unless it's a 50 cal or something insane.   

       So bottom line, nothing sounds more impressive than a backfire. A gun won't rattle your windows, a good backfire will.
doctorremulac3, Oct 20 2012

       Even a .50 has a fairly sharp report compared to a backfiring engine. Most guns don't sound much like they do in the movies (even in otaku-scale realistic war movies like Saving Private Ryan). From a distance, a shotgun makes a sort of booming sound, but rifles and handguns all tend to make a pop or crack that does not translate well to recording media--thus the altered/amended sounds you hear in the theater. The really impressive part of a gunshot (aside from the knowledge that it is a sound made by a gun) is felt rather than heard; standing next to a .50- cal machinegun feels like being repeatedly whacked in the chest with a shovel (unless you're not wearing earplugs, in which case it feels like being repeatedly whacked in the _brain_ with a shovel).   

       The most realistic gunshot I've ever heard in a movie is the suppressor-equipped 9mm at the end of 'The Bourne Identity' (K-THWACK!).
Alterother, Oct 20 2012

       Did a bit of sound design back in the day for music percussion tracks, not for movies but the technique was the same. You layer all sorts of stuff together to make those big gun sounds. Firecrackers in 50 gallon drums, thunder, sonic booms. Got a great snair drum sound from a pile driver down the street once. You detune them, cut them up, time compress them, distortion, e.q. all sorts of crazy stuff. It can be quite fun. All to be able to say "Hey, listen to this..." "BLOOWWAAAMMOOWW!" when somebody walks into the studio.   

       Just to make the point of how much the gun sounds are modified for movies, take a copy of The Expendables for instance, and replace the soundtrack with a recording of a shooting range. It'll sound like they're quietly fighting while somebody's popping popcorn.
doctorremulac3, Oct 20 2012

       Yeah, I was riding my bicycle, one time, coasting downhill, and some goober driving a big school bus decided to pass. The backfire was only a few feet away, with the exhaust pipe pointing at me. It was louder than the time I fired a big shotgun with no ear protection. It sounded more like a gun than a gun does.   

       On the other hand, when I was riding the front-wheel drive motorcycle with the engine right in front of the handlebars, and little stub exhausts, I loved to back off the throttle just to see the flames pop.
baconbrain, Oct 21 2012

       As an Über-gun-nut who's actually fired andor been present during the firing of nearly all of the badass/historical guns you typically see in movies, the thing that probably drives me furthest up the walls is when they have a minigun in the movie, yet the sound guys use a sped-up M60 with added blasting and ejection rattle. I understand that the moviegoing public is probably put off by seeing what is very obviously a gun but hearing something that doesn't sound much like a gun, but one of the scariest things about powered gats like the minigun is that they _don't_ sound like guns.   

       Sorry. Rant suspended.
Alterother, Oct 21 2012

       //some goober driving a big school bus// hah! gotcha!   

       Actually, it wasn't me, nor even my bus nor my route... but one of the bus routes to my high school was nearly 70 miles one way, and passed through a national park. In the which there was a goodly concentration of orchards - and deer. ([Alterother], beware.) Since the deer were wont to wander, or leap, into the path of the bus, the driver would just turn the ignition key to "off" for a couple of seconds, then back on; about 3 shots over the course of a mile or so, and the bus would safely traverse the park with no mule-deer hood ornamentation.   

       I don't know if the park rangers ever caught up with those nasty "poachers" they were chasing every morning...
lurch, Oct 21 2012

       Clever... My Jeep will do the same thing. Of course, my Jeep has a nigh-indestructible scratch-built bumper and brush guard specifically design for catching the odd wayward deer, but I'll still try it out.
Alterother, Oct 21 2012

       What everyone else said.   

       The acoustic signature of firearm discharge is notable for its very short rise time. A lot of the energy is in this pulse; there's almost no resonance or oscillation. It's effectively a soliton (saltire) wave.   

       The noticeable thing about small arms fire in an urban environment is the high-frequency "screech" as this pulse echoes back off planar surfaces in the vicinity; typically, these surfaces reflect better for high than low frequencies.   

       A tailpipe is going to smear the pulse excessively if it originates in the manifold. Better to design a way of injecting fuel into the end of the pipe and then igniting it.   

       For realism, the quality required is a very short rise time for the sound.
8th of 7, Oct 21 2012

       // high-frequency "screech" as this pulse echoes back off planar surfaces in the vicinity //   

       Heh. I was firing off firecrackers (illegally), just down the block from a stadium with a corrugated front---square ridges about a foot wide and deep---and the echo was fascinating. Which is why I kept setting off the firecrackers.   

       (They say the Mayan pyramids give off a echo that screeches like a sacred bird.)   

       I got to stand at attention through a 21-gun cannon salute, once, where the cannon (firing blanks) was pointed across the bay at a bunch of houses/buildings that were facing us. The echoes were sharp and distinct off each individual house front.
baconbrain, Oct 21 2012

       //For realism, the quality required is...//   

       Fortunately, most of the people who will hear it will only have heard guns on TV, so I suspect an unrealistic sound will sound more realistic.
MaxwellBuchanan, Oct 21 2012

       That's actually quite profound, in a sad way.   

       For the same reasons, movie "explosions" are lavish with hydrocarbon fuels. In reality, high explosives produce a brief, bright flash entirely lacking the spectacular roiling fireball beloved of Hollywood. The real thing looks much less dramatic; but in a cinema, it's impossible to convey the ground shock/air shock that is so entrancingly rapturous, nor the whirr and fizz of small pieces of debris passing through the air at supersonic speeds …   

       We are very much in favour of increased reality in movies. If that means patrons leave the theatre deafened, disorientated, mildly concussed and bleeding from multiple superficial wounds then so be it. And that's just the trailer … the main feature would be considerably more impressive.
8th of 7, Oct 21 2012

       If I remember my Start Reck, the Borg use lasers which make a zzzzbing noise even in deep space. Presumably, they do this in order to intimidate the enemy.   

       By the same token, it seems to me that current firearms and explosives need considerable revision to make them more lifelike.   

       <placeholder for [8th] comment regarding lasers being primitive weapons>_ <\placeholder>   

       <placeholder for [8th] to make a pun/play on the word 'lifelike'> _ <\placeholder>
MaxwellBuchanan, Oct 21 2012

       // Better to design a way of injecting fuel into the end of the pipe and then igniting it. //   

       Also WKTE.   

       // We are very much in favour of increased reality in movies. //   

       As are I. Back to Saving Private Ryan for a moment: despite the conservatively enhanced gunshots (they did their best to keep it real), I was impressed with the non-fiery, terrifyingly instant ordnance explosions in the movie. The mortars went Crump!, the grenades went G- Whack!, and the bombs simply went Bang! with little melodramatics and no excess of sturm und drang, just a whole lot of schrapnel and a horrific (simulated) toll on human life. I have it on good authority, mainly from [8th] and a handful of WWII vets, that these at least were highly realistic depictions. The tank cannons still had a little too much slow boom, but you have to depict scale somehow. Since then, I've been quite (objectively) pleased at the trend of 'realistic' violence in action movies, emphasizing the terror and carnage and moving away from the pretty fireworks. Gunshots, however, will never sound just right, and I fear we may never hear a true minigun blast in the theater. 'We Were Soldiers' came close, but even then they slowed it down.
Alterother, Oct 21 2012

       My dad and son were both in combat so my combat stories are all second hand. My personal war stories are mostly about things like getting snowed in for a day in Pittsburg without room service and being forced to eat at the Denny's next door. It's still hard to talk about it.   

       Anyway, my boy tells me that the sound of a helicopter minigun, especially at night was very creepy sounding. Very un-gunlike, more like a growling sound with these tendrils of fiery death reaching down from the sky. I think he used the word "creepy", but now that I think if it the word might have been "awesome". I'll have to check with him. Anyway it's supposedly a sound you'll never forget.
doctorremulac3, Oct 21 2012

       It isn't. I've never been in combat, but I've used/witnessed many combat weapons on the range. A minigun sounds like a low-octave chainsaw from Hell. It's the sound you'd expect if the Grim Reaper mechanized his scythe. It's indescribably loud, louder than a jet engine, and if you close your mouth while you're standing nearby it tries to push your sinuses out through your eyeballs (or ears, possibly; I'm always wearing earplugs at these events).
Alterother, Oct 21 2012

       By the way speaking of combat depicted in the theater, my dad says the beach scene from Saving Private Ryan was the only realistic depiction of battle he's ever seen in a movie. He said the only thing missing was the smells which are pretty unmistakable evidently. By his account battle was an extremely horrific business. I think he used the words "scary" and "confusing". I can only imagine.
doctorremulac3, Oct 21 2012

       It seems to me that tweaking the car ignition would leave Max capable of making only one sound. Instruments are all electronic these days. Why not get more breadth of expression: loudspeakers of the "Baby Got Back" variety and sampled sounds of various sorts. If nothing else a range of different backfires, but why not screeching brakes, train air horns, roaring race car engines, snorting Belgians, urinating on a car door, and so on. All those useful sounds.
bungston, Oct 21 2012

       Loudspeakers? A trifle vulgar, but an interesting option.   

       Actually, I wonder if there's also a market to be made in guns engineered to sound like a car backfiring?
MaxwellBuchanan, Oct 21 2012

       // snowed in for a day in Pittsburg without room service and being forced to eat at the Denny's next door. It's still hard to talk about it //   

       Understandable. Christmas 1942 in Stalingrad would be infinitely preferable.   

       For spine chilling never-to-be-forgotten audio impact, the 30mm cannon in a Thunderbolt has few competitors even as some distance.   

       Memorable sounds? Being 2km forward of a squadron of Challenger tanks and listening to outgoing rounds passing low overhead; the staggering sensation of a MLRS releasing a full salvo; and, oddly, the unmistakeable relentless hammering of a .303 Vickers gun.   

       As to Saving Private Ryan- yes, the first time that the film industry got the WipWipWip of incoming automatic weapons fire right. Once heard, never forgotten.
8th of 7, Oct 21 2012

       //Memorable sounds? Being 2km forward of a squadron of Challenger tanks and listening to outgoing rounds passing low overhead; the staggering sensation of a MLRS releasing a full salvo; and, oddly, the unmistakeable relentless hammering of a .303 Vickers gun.//   

       Gosh, [8th], you do get around, don't you. When was all this?
MaxwellBuchanan, Oct 21 2012

       Yea 8, were you over in the Sandbox with the Brits? If so, what part? If you say "The hot sh*tty part." I'll know you were really there. (That's the standard line I hear.)
doctorremulac3, Oct 21 2012

       I'm interested to know why you all think it's so hard to get gunfire sounding right in films. I mean - reasonably expensive microphone, requisite gun, relative placement & environment, one round[2]. Job done - to the limit of the speakers available. If the speakers arn't up to the job that's not the film's fault.   

       [2] Or a few for variety. Or, say, 200 for a minigun.
Loris, Oct 21 2012

       // When was all this? //   

       Every Tuesday afternoon, between 1330 and 1530 (if wet, in the Church Hall). Tea or coffee and biscuits are included, but please bring your own mug, teaspoon, folding chair, body armour and helmet. Sturdy shoes, ear defenders and full anti-flash gear are recommended.   

       // if you say "The hot sh*tty part." I'll know you were really there //   

       Ummm … warm certainly, dusty definitely, smelly - incredibly. It's just a matter of picking the right time of year to visit, which is restricted to the 29th of February.   

       // Job done //   

       No. The peak SPL from even a modest firearm at 5 metres is going to be 130dBA or more. To reproduce that, you'd need a massive amplifier system and enough speakers to handle the power and even then the surge would probably fry the crossovers.   

       Go hook up a quality microphone to a storage scope and then loose off a few rounds. Check out the peak height and the rise time. Oh, and don't expect the mic to be good for anything afterwards.
8th of 7, Oct 21 2012

       I think the argument is that real guns do not sound very realistic, and therefore the sound of real gunfire is not used.   

       In the end, though, you have to ask yourself who is at fault here. If the vast majority of people think that real guns don't make realistic gunfire noises, it's clearly the guns that need revising.
MaxwellBuchanan, Oct 21 2012

       There's always that delightful Russian musical instrument, the Stalin Organ …   

8th of 7, Oct 21 2012

       I'm not sure 'realism' is the issue; I think it's more that real guns don't sound _impressive_ enough on film. Dirty Harry's big bad .44 magnum is a very impressive gun on celluloid and in real life, but the genuine article just goes pop when you pull the trigger. Granted, it's a very loud pop, but it's over very quickly and doesn't sound like much more than a highly amplified champagne cork.   

       Truth be told, a magnum doesn't even sound that impressive first-hand (at least for those who are accustomed to gunfire). For the very real harm and devastation such a hand cannon causes to be fully conveyed to the audience, it has to do more than just go 'pop'! Thus, instead of sourcing actual gunfire, foley artists turned to firecrackers in trash cans for a deeper, fuller bang.   

       Nowadays, with all the digital sound manipulation wizardry that's being developed, filmmakers are turning back to real gunshots recorded in studio environs, but they still have to mess with them to make them spectacular enough to match what's happening on the screen. I'm not even really bothered by that; what bugs me is when some mobster's snubnose .38 goes off with a bang that I clearly recognize as having originated with a 30-06 rifle, or when an automatic weapon goes ticktickticktick to let us know that it's empty, even though in reality the last shot sounds sharp and cut-off because the slide is locked back.
Alterother, Oct 21 2012

       //I think the argument is that real guns do not sound very realistic//   

       Certainly not when compared to preconceptions created by years of hearing sound designed, dramatized gunshots in movies.   

       And in the category: Best gun sound in a movie, the nominees are: "Big gun. The Expendables 2" (See link, fast forward to 1:37)
doctorremulac3, Oct 21 2012

       I believe that [alterother] has succinctly and peraciously hit the nail on the head and come straight to the point.
MaxwellBuchanan, Oct 21 2012

       'cues'... 'unlimitless'... ?   

       what am I missing?
Phrontistery, Oct 22 2012

       //all that's needed is a switch which would cut the ignition to a single sparkplug for one cycle?//   

       Hmm… I dunno about that. I'm not going to say it wouldn't work, but I can tell you that I once had a Corvette with a faulty spark plug boot, and the only thing I noticed was that it ran like crap at idle. The whole engine would nearly vibrate itself to pieces. Once it got going you almost couldn't tell it was running on only 7 cylinders, though. I certainly didn't hear any backfiring.   

       I have a feeling that for a modern computer-controlled, fuel- injected engine fitted with a catalytic converter, it may be quite a bit more complicated than simply cutting out the spark for a single cycle.
ytk, Oct 22 2012

       Perhaps though it's the non-realism of movie gunfire sounds which gives movie bullets enough momentum to push people through plate-glass windows? So, let's suppose that movie bullets contain 1mm^3 of material which Hollywood has collected from the core of a white dwarf star. This has a density of 1x10^9 kg/m^3, so the bullet will weigh just about 1kg. If it is fired at 200 m/s it will therefore have sufficient momentum to give a 100kg man a velocity of 2m/s towards the nearest plate-glass window. Surely the explosive power necessary to propel a 1kg bullet, in addition to the retro-rockets required to stop the shooter moving backwards at 2 m/s (Newton, and all that), would make a more impressive noise than 'real' gunfire?
hippo, Oct 22 2012

       No degenerate matter required, except perhaps in the brains (if any) of the scriptwriters. Rather, it is an example of how the phenomenon of Cartoon Physics <link> has permeated the world of live-action movies.
8th of 7, Oct 22 2012

       What you need is a veteran car - I'd imagine Maxwell Towers to have at least a few.   

       Since they have many more manual controls than moderns, one can switch off the ignition while driving down a hill. If you put your foot down for a short time, the exhaust pipe should become filled with petrol and air and is thus primed. On reaching the bottom (or passing a cyclist struggling up in the other direction) one can fully retard the ignition and switch the magneto back on. Hill-arity will ensue. Probably works best in a lower gear since the engine speed will be greater and therefore the effect of retarding the ignition will be greater - this is the reason why it will be less reliable on an unmodified modern (high engine speed = advanced ignition, except on steep hills upwards)   

       I haven't tried this out yet, but is close to the top of things to try when I've done my clutch up.
TomP, Oct 22 2012

       just get an older Class B rally car. The anti-lag systems were ridiculous.
WcW, Oct 22 2012

       If foley artists make gun-noises that sound like movie gun noised by setting off bangers in a bin, could guns not be made to sound as the washed majority think they sound simply by puncturing a hole in the bottom of a metal bin and sticking the the fore of the gun through the hole, the aft (including the handle) remaining outwith and behind the bin. When fired, the binchamber may or may not create a large echoey booming noise, which will sound boss. This approach has the added bonuses of giving the wielder something to catch enemy bullets in and of making the firearm easier to disguise (as a bin).   

       I realise that this does not address the problem set out by MaxwellBuchanan (ch is aspirated) but hey ho. That problem could be solved by sitting a foley artist in the boot with a metal bin and some fireworks.
calum, Oct 22 2012

       [calum], you should post that as a new idea. I would also suggest electronic versions, perhaps a jacket-mounted speaker system that senses the 'crack' and amplifies and echoes it.
pocmloc, Oct 22 2012

       Done. Feel free to suggest.   

       [bigsleep], do what? (Remind me of the babe)
calum, Oct 22 2012

       Hang on - 130 decibels and it isn't impressive enough?   

       To be honest I don't think I'd mind if the gunfire wasn't impressive. And realism in war films would be great.   

       Protagonist gets conscripted
Protagonist wades through muddy field getting shouted at.
Protagonist travels to front. Mostly involves being sick, bored etc.
Protagonist arrives at front. More hanging around. Occasionally something some distance away will be hit etc; generally doesn't sound impressive.
Protagonist goes on mission, catches a bullet, dies screaming, fade to black.
Loris, Oct 22 2012

       You missed the bits about being too hot/ thirsty/cold/wet/hungry, but particularly the digging holes … lots of digging holes. "Holes every day … dying- occasionally".
8th of 7, Oct 22 2012

       [Loris], you need to watch 'The Pacific'. It's what you described (i.e. a realistic vision of war) as seen through the eyes of those who opted out on the last step.
Alterother, Oct 22 2012

       And listen to the veterans in "Band Of Brothers".
8th of 7, Oct 22 2012


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