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In The Enemy Below (at 1:21:18/1:37:35), the USN XO fires one round from his pistol into mattresses that sailors have poured gasoline on. Next these mattresses fire up. Is this scientific?

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  • USN XO = united states navy executive officer?
    – npst
    Oct 25 at 12:26
  • @npst yes. i just copied "XO" from that shooter's helmet.
    – user91864
    Oct 26 at 6:34
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    If the mattress is on concrete/tarmac I would imagine the bullet would spark upon impact. Also if the gun is close enough, muzzle flare would likely do the trick. Recommend you experiment and get back to us.
    – P i
    Oct 26 at 9:00
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Not particularly scientific, no.

You need an ignition source to start a fire, and a regular bullet is simply a lump of metal. In theory, if the bullet hit a another surface it might spark, but Mythbusters tried very hard to ignite a vehicle's gas tank once. Even with an incendiary/tracer bullet shooting into a tank of vapour, they just couldn't get it done.

Mattresses soaked in gasoline probably wouldn't provide enough opportunity to soak and ignite.

Edit:

I couldn't view the video in the original version of the question and was unaware that the officer was using a flare gun. This somewhat changes the situation, and it is much more likely that the gasoline vapour will ignite which will then ignite the gasoline-soaked mattresses

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    Also, there will be no oxygen (part 2 of the fire triangle) inside the mattresses, and there will be no fuel (part 1 of the fire triangle) outside the mattresses. There is only a thin layer around the mattresses where there is the right mixture ratio of gasoline fumes and air to even be ignitable, and that's what you need to ignite. The gas layer above the mattress, not the mattress itself. Oct 24 at 14:51
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    There's theoretically at least some chance that shooting a vehicle might cause some sparks based on the bullet scraping against metal (though as the Mythbusters showed even this wasn't enough in their test). Shooting some soft mattresses, no matter what they're soaked in, would almost certainly not work. (Unless it was a flare gun as it apparently was.) These particular mattresses don't even look like they have metal springs in them, they're just soft pads. Nothing to make a spark against. Oct 25 at 16:58
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    Mythbusters didn't try to use muzzle flash, which seems fairly relevant here.
    – fectin
    Oct 26 at 2:41
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    I think the problem we encounter in fiction is that writers assume that dangerous activities reliably produce the feared result. You see this a lot in murder mysteries where the murderer kills by creating an electrical risk which in real life only kills when a series of additional conditions are accidentally met by the victim.
    – David42
    Oct 26 at 12:58
  • @David42 In other words, there's a difference between "deadly", "lethal" and "fatal". Oct 26 at 22:51
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As the other answer states, a single actual standard bullet would not ignite that way.

However, in the movie, it seems clear that the officer is not using a standard handgun but rather a flare gun of some kind.

Granted that this is hard to make out in the somewhat darkened scene but the sound, shape and action do seem to bear this out.

enter image description here

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    It might be worth explaining that a flare gun fires a projectile that is actually on fire, or at least linking to the Wikipedia article on flares; not everyone knows what they are.
    – zwol
    Oct 24 at 22:29
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    For completeness' sake: Flare Gun Wikipedia article.
    – MC Emperor
    Oct 25 at 8:20
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    This answer would be better if you could show an example of a flare gun that looks like the weapon on screen. The gun he shoots looks more like a standard issue .45 caliber hand gun like a 1911 rather than a flare gun which have something like a 1"+ diameter round barrel. Also, the large and relatively low velocity flare projectile would most likely just bounce off the mattresses, but I admit it could ignite them.
    – JPhi1618
    Oct 25 at 20:49
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    @JPhi1618 something like columbusmuseum.pastperfectonline.com/webobject/… Sedgley Signal Pistol Mark 5 perhaps? "These types of flare pistols were used during World War II by the U.S. Navy for signaling and to fire parachute flares to illuminate the night." Oct 26 at 2:43
  • @JamesMoore that’s a good find. Very pistol looking without an out of proportion barrel like most.
    – JPhi1618
    Oct 26 at 3:00

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