Georgia Firearm Forums - Georgia Packing banner
1 - 20 of 48 Posts

·
Registered
Joined
·
1,367 Posts
Butter, if you could do that with your P7 you could boil the water and make pasta. :D
 

·
Registered
Joined
·
4,864 Posts
Don't think of it as fighting in a trashcan full of water.

Think of it as you just grabbed you pistol from the bottom of a puddle where it went when the guy who is trying to kill you knocked it out of your hand. Now would you want to grab a pistol and shoot someone trying to kill you from under water and know it would work? and not require anything more than a trigger pull?
 

·
Registered
Joined
·
1,733 Posts
Discussion Starter · #8 ·
On a slightly related note: The 2004 film "Mindhunters" features 1911s firing underwater [to little effect]. It also has a sabotaged Glock pulling a Beretta-style catastrophic slide failure.
 

·
Registered
Joined
·
1,981 Posts
Bullets don't travel the same as underwater as they do in air. They go much shorter distances with much less power. So, Shooting someone underwater may not be a great idea even if the gun is a water pistol.

Then again, I saw a demo for a Sphinx 9mm that put a hole in wood target underwater, fired by a diver.
 

·
Registered
Joined
·
4,226 Posts
tace said:
Bullets don't travel the same as underwater as they do in air. They go much shorter distances with much less power. So, Shooting someone underwater may not be a great idea even if the gun is a water pistol.

Then again, I saw a demo for a Sphinx 9mm that put a hole in wood target underwater, fired by a diver.
Although they don't always use real scientific experiments in their show, I did see a MythBusters episode where they shot a lot of different firearms both underwater and into standing water. It appeared to me that the faster the round moved the more apt it was to disentigrate when it hit the water. Shooting while underwater was in many cases an exercise in futility as many rounds didn't travel far or with any penetrating power. The shotgun they shot underwater basically exploded.
 

·
Registered
Joined
·
2,188 Posts
Remember water is heavy and the deeper you submerge the firearm the more pressure and weight you have in the barrel, at some point you are going to lose your normal least path of resistance better known as the barrel, then who knows where it is going to be.
 

·
Registered
Joined
·
4,864 Posts
Firearmz said:
Remember water is heavy and the deeper you submerge the firearm the more pressure and weight you have in the barrel, at some point you are going to lose your normal least path of resistance better known as the barrel, then who knows where it is going to be.
I'm not saying this to be contrary but here goes...

You are 100% correct that the deeper you submerge a pistol the more pressure is exerted on it. However that pressure is exerted on all of it. meaning that yes the bullet has to push, oh say 20psi for a nice round number, out of the barrel to move in a forward direction. However, that same 20psi is also exerting itself on the barrel and slide. This "pressure reinforcement" continues to keep the open end of the barrel the path of least resistance.

End result is the round will still go out the end of the barrel, with 35,000 PSI behind the barrel the 20PSI just loses out, of course that 20PSI will slow down the bullet alot faster than 10psi.
 

·
Registered
Joined
·
6,313 Posts
Firearmz said:
Remember water is heavy and the deeper you submerge the firearm the more pressure and weight you have in the barrel, at some point you are going to lose your normal least path of resistance better known as the barrel, then who knows where it is going to be.
32 ft (fresh water) = 1 atm = 14.92 psi (std day)

For salt water, make that 33 ft.

At the operating depths of human beings, water pressure is not a significant factor for the gun. And when I say the gun, I'm talking about the water pressure deforming the actual parts of the gun.

The ability of the round to displace water out of the barrel is a function of water density. Compressibility does not become a factor until a depth on the order of 1000's of feet are reached.

Ammunition is a different story. One can derive experimentally, the force required to force the bullet back into the casing from the crimp, thus flooding the casing, and rendering the powder inoperable (powder still doesn't fire when wet, correct?) From this value, one can predict a depth at which the cartridge will fail.

This of course assumes that the case does not buckling inward initially, thus providing additional strength to the crimp.

This also assumes that the cartridge fails when the bullet separates completely from the crimp. A more detailed experiment would be required to account for slow leaking into the cartridge.

(Thanks Ken, for the opportunity to display my nerd-fu)

/why yes, I am a rocket scientist :)
 

·
Super Moderator
Joined
·
16,485 Posts
AeroShooter said:
At the operating depths of human beings, water pressure is not a significant factor for the gun. And when I say the gun, I'm talking about the water pressure deforming the actual parts of the gun.
Sure, but a lot more pressure will build up in the barrel before the bullet exits.

Ammunition is a different story. One can derive experimentally, the force required to force the bullet back into the casing from the crimp, thus flooding the casing, and rendering the powder inoperable (powder still doesn't fire when wet, correct?) From this value, one can predict a depth at which the cartridge will fail.
Powder should burn when wet, though maybe not as fast/completely.
 

·
Registered
Joined
·
1,733 Posts
Discussion Starter · #17 ·
The effects of the water pressure on the gun are minimal. I had the reverse argument some time ago when discussing Guns In Space. One guy assumed that the gun would explode due to the lack of outside pressure. I gave him the same argument presented here- atmospheric pressure levels are negligible compared to the internal pressures of a firing gun.
 

·
Registered
Joined
·
2,139 Posts
Aeroshooter is correct. Water pressure is not the issue at all with firing under water. The primary issues of concern relate to the ballistics changes due to the increased mass density of the water, viscosity, and incompressbility. Depending on the shape of the round, you will have a substantial added mass effect. A hollow point will now push along ahead of it the water in it's hollow, plus a cone out front, once out of the barrel. Inside the barrel, the bullet will have to accelerate the entire water column in front of it, rather than simply compressing the air in front of it in the barrel. The much greater 'added mass' in the barrel will change the pressure, volume, temperature relationship of the powder burn. I'm not sure what effect this would have. The drag will skyrocket due the to the density change. I would expect that guns would be essentially useless under water except at very close ranges.

I, too, am in fact a rocket scientist (at least by undergraduate education).
 
1 - 20 of 48 Posts
Top