Would being in water greatly change the effect of a gun shot? Would it be slowed down materially? Or would it only be a material change over a long distance?
Question is the result of a “dinner debate” where someone quoting TV as a reliable source said it doesn’t matter? If it happens on TV, it must be real??
Yes it will greatly affect the range. For example a .22 long rifle rimfire bullet fired from a 4" barrel revolver might have a range, distance traveled, somewhat short of a mile if aimed above the horizontal.
The same bullet will not travel 5-6 feet in water. Water traps used in ballistics labs are somewhat shorter than 10 feet and will stop most handgun and many rifle bullets.
Water drastically slows down bullets. To the point they become nonlethal within a few feet - depending on the type of weapon, the bullet and the amount of powder. Police ballistics labs use a water tank to capture bullets for comparision, as seen on crime dramas like CSI. Of course, at point blank range, you’re still dead.
Yes, water has a much greater coefficient of drag than air, and any bullet fired into water would slow to it’s leisurely terminal velocity after a couple of metres or less. You could then quite safely catch it in your hand.
So the next time you’re bobbing around in the ocean being strafed by enemy aircraft, swim downwards…
I presume you mean a bullet fired in air, entering water and hitting a target underwater?
Firing a weapon underwater is a whole 'nother kettle of fish.
OK, so the bullet comes at the surface. If the bullet approached at something like a parallel to the surface of the water we have an excellent chance for the round to skip. The physics of this are well-understood, but not by me. Suffice it to say that the round would most likely be massively deformed by its contact with the water.
If the round does break the surface, again we may expect at least some deformation. Water is 900 (600?) time denser than air and bullets are simply not designed for this kind of abuse. It would then enter the world of internal ballistics. It would dump several thousand hogsheads of energy into fortnight of water it passes through. Very quickly, say in a meter or so, it would have just about none of the energy imparted by the weapon left.
All in all, being underwater is a good place to be when being shot at.
Anecdotal: During WWII, UD specialists used to be able to catch Japanese bullets that were fired at them from shore if they were a few meters under water.
I have seen video of UDT guy watching 50 cal bullets enter the water. They would travel for about 5-8 feet slowing down then stop and just drop to the bottom.
Nitpick…the drag coefficient isn’t a function of the fluid. It’s determined mostly by the geometry of the object. The viscosity of a fluid can affect the resultant C[sub]D[/sub] of the object, but it’s still object-dependent.
The issue is that water has a much greater density than air. That’s because the formula for the drag force that decelerates the bullet is:
D = ½rV² · S[sub]ref[/sub] · C[sub]D[/sub]
S[sub]ref[/sub] is the reference are of the object, usually the frontal projected area
r is density, which is about 800 times higher for water than air.
Therefore, at the same muzzle velocity, the bullet will experience about 800 times as much force trying to slow it down. It’s more complicated than that in reality…once viscosity, cavitation, and you-name-it get factored in. But there’s your order-of-magnitude feel for it.
Firing a gun of any kind under water would be a very hazardous if not lethal undertaking. With water in the barrel it would most likey explode the barrell or fracture the frame with disasterous consequence to the person holding the gun. IOW DON’T.
:rolleyes:
TV shows in general are not reliable sources of factual/scientific information as the writers are abysmally ignorant of facts, figures, and scientific information. They write for dramatic effect.
I read a Scientific American article a few years back about shapes designed to allow extremely high velocities under water. One such shape is being tested as an antisubmarine projectile - think aircraft with an autocannon that can strafe submarines some distance underwater.
Don’t remember all the details but I’ll dig around for the article.
OK, that was easy, here’s a link to SciAm, you can read the synopsis and download the article ($) if you want. Or go to the library 
Sorry, spring, maybe with low quality “saturday night specials,” but modern brand-name firearms, this doesn’t hold true. (Tests were done in the 70’s. The bullets went about 10 feet [.38 Special]). Can’t speak for semi-auto’s though.
Is the shockwave from the explosion of the powder (assuming the gun remains intact) dangerous? I’m thinking of the “fishing with dynamite” thing. I reallize that that’s a much much bigger explosion.
Over at one of the larger gun boards, someone posted pictures of what happened when he fired his AR-15 type rifle underwater. Sufficient to say, he is lucky to have not sufferered injury. At another board pictures were posted of a SW 629 that was fired underwater; the cylinder ruptured, and that is no mean feat on that pistol.
Even if you put those maritime springcups on your G17, your really shouldn’t fire it underwater. Guns+underwater=not safe.
So we got mixed results. Some guns fail, some don’t. Looks like a good case for not doing it. I don’t recall the model numbers that were tested successfully, just the caliber and make (S&W).
Hogsheads? Fortnight? Are you firing a blunderbuss, or some other type of gunne?
I believe the metric equivalent would ‘cubic hectares’ plotted over ‘kilopixels.’
I believe you’ll find the* Difinitive list of Equialents*Here 