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05-13-1999, 06:08 AM
I recently read a book by Clive Cussler where there was a small battle on the moon and the Americans won partly by using a .22 caliber rifle. The advantage was no one could see the shots being fired and no one could hear them so nobody knew where they were coming from. It seems to me that the gun shouldn't have been able to fire at all as there was no oxygen for the combustion to take place propelling the bullet out of the cartridge.

So, would a normal gun fire in outer space?

Also, would a gun work underwater? You see this occasionally in Hollywood, but the water in the barrel of the gun would block the bullet causing the gun to explode, wouldn't it?

05-13-1999, 06:41 AM
Hmmm... something tells me this is one of those that you dont quite know unless you do it, but, I will say I think the gun does fire in space or on the moon - lets say on the surface of the moon. Not that I am an expert, but bullet casings are sealed and the explosion takes place inside that little space giving you that awesome propelling force.. things can burn in space.. otherwise there would be no stars! I would think you could see a brief flash, but no, you wouldnt hear it thats for sure.. the interesting part is (depending on your aim) the bullet path would be pretty constant due to 1/6th the gravity of earth.

As for firing underwater.. ya got me.. I have heard of some special guns can do this but it was just talk, no facts I know of.

Of course I could be wrong! :)

05-13-1999, 09:06 AM
Yes, theoperaghost, a bullet would indeed fire on the moon for the reason explained by Neobican.

But shooting on the moon would be a very, very different experience than shooting on Earth. You know that Ďkickí you feel when you fire a gun? Itís the embodiment of Newtonís 3rd law of the conservation of energy: ďFor every action, there is an equal, yet opposite, reaction.Ē

On the earth, the force of the gunís recoil pushes you back with the same force with which the bullet is propelled forward (the reason you only feel a small kick, though, is because the force that propels the 20 gram bullet forward with enough energy to kill is acting backward against your mass of maybe 80 kilograms -- or 4,000 times more mass). On Earth, the force of gravity is more than sufficient to keep your feet firmly planted against the recoil.

But itís a different story on the moon. With only about 1/6 of Earthís gravity, the kick of the recoil would likely be enough to overcome the paltry force of the moonís gravity acting on you. The result: youíd go flying backwards. The only way to safely shoot on the moon would be either in a prone position (in which case youíd still be thrown backwards, though with less drastic results because youíre already on the ground), or firmly braced against an immovable object.

Shooting at someone in free space would be a suicide mission. Newtonís laws still apply (and are, in fact, made all the more evident without the domineering power of Earthís gravity). The bullet would indeed go forward, and you would go back, and back, and back ...

(As a complete aside, Newtonís laws are so obvious outside a strong gravitational force that skews everything that itís been said that had humankind evolved in a place with low gravity, we would have come up with the laws of motion before we came up with the wheel.)

As to your second question, shooting a gun under water isnít much different than shooting on land. the water in the barrel of the gun would block the bullet causing the gun to explode

No more than the air in the barrel would block a bullet; the bullet has to travel through the medium of water just as it has to travel through the medium of air, pushing either medium aside as it goes. But water is thousands of times more dense than air, so the bullet would travel much slower and be stopped much sooner. Of course, if you went very, very deep into the ocean, I suppose you might get to a depth where the pressure of the water is so great that it would be easier for the barrel to explode than it would be to expel the bullet into that great pressure (of course, by that pressure, the gun -- not to mention you -- would probably be crushed, so itís a moot point anyway).

Finally on this topic, my above explanations of underwater firing assume the water has not breached the bulletís casing and soaked the powder, in which case the bullet wouldnít fire.


On an entirely unrelated topic, I have to respond to Neobicanís comment:
things can burn in space.. otherwise there would be no stars!

Please do not confuse a Ďburningí star with combustion as it happens on Earth. The process that makes a star glow has nothing whatsoever to do with combustion. Instead, it is the process of fusing the atoms of two elements together to produce a new element. In the case of a young star such as ours, itís two hydrogen atoms fusing into one helium atom -- a process that has nothing to do with combustion and takes place without the presence of oxygen.


~ Complacency is far more dangerous than outrage

05-13-1999, 09:06 AM
- - - The gun don't need any more air to fire than what's already inside the cartridge. NATO bullets have a laquer seal to improve water resistance, but I don't think it's considered airtight. Ammunition for use in space isn't a topic reloading manuals explore very much. Yet.
- - - Guns that fire underwater is easy - all they use is a thin metal or plastic cap on the "exit" end of the barrel. The (special) gun fits together well enough that water won't get into the barrel, but they're only meant for use a few yards below the surface. The cap is thick enough to keep water out but thin enough that the bullet can pass through it and/or blow it off. You can only fire through that particular barrel once under water. There was a SEAL-type gun in a magazine I saw some time back that had six underwater shots - and six barrels. - I've never heard of any gun that could fire submerged, with the barrel full of water. - MC, former gun-nut

05-13-1999, 09:22 AM
It's true that being physically located "in space" does not prevent things from burning, but oxygen must be present to support the combustion. Spacecraft carry tanks of oxidants (oxygen-containing chemicals) which they combine with the fuel to make fire.

Note that stars don't really burn. Earthly fires involve a chemical reaction that releases energy. A star's heat comes from nuclear fusion, which does not require oxygen, and releases a lot more (a LOT more) energy.

But back to the guns. There are two kinds of explosive in most cartridges. First is the primer, which is very volatile, and explodes when hit by the firing pin. Second is the propellant, the actual gunpowder, which is more stable; it's ignited by the explosion of the primer. Also, the propellant doesn't actually explode, it just burns very fast.

IIRC, the primer contains an oxidant, which is what makes it so easy to ignite. The propellant depends on oxygen from the air. So firing a standard rifle on the moon would create a very tiny explosion as the primer went off, but the bullet wouldn't actually go anywhere. However, it might be possible to create bullets that would fire on the moon, by incorporating an oxidant in the propellant; maybe one of the chemistry wonks could tell us if that would be feasible.

As for working underwater, I don't really know. I believe there is enough free oxygen in the sea to support combustion; this is why magnesium flares work there. Ordinary fires don't burn because the water draws heat away so quickly that the reaction can't sustain itself. On the one hand, a bullet's firing happens so quickly that loss of heat via the water shouldn't be an issue; on the other hand, wet gunpowder doesn't burn right. So maybe it'd work, as long as the gun wasn't underwater long enough for the cartridge to get waterlogged.

05-13-1999, 09:25 AM
Damn, beaten to the punch again... I need to learn to type faster.

05-13-1999, 09:37 AM
Sheesh! One would think its the supreme court trying to decipher the meaning of the constitution... you guys dont have to be so anal-retentive to responses when you know darn well what I meant. Of course things can BURN (I said it again) in space, meaning explosions, fusion, combustion with your oxidants, etc... I will be the first to admit if I am wrong but try not to take my selection of vocabulary like its the holy gospel.

05-13-1999, 09:45 AM
AuraSeer: Let me admit for the record that Iím no expert on munitions. I just know my physics. But, Iím going to argue munitions anyway ...

The propellant depends on oxygen from the air. So firing a standard rifle on the moon would create a very tiny explosion as the primer went off, but the bullet wouldn't actually go anywhere.

I disagree. Itís my understanding that the casing containing the primer and gunpowder has all the oxygen needed to sustain the reaction; the gunpowder needs no outside oxygen. If it did, the bullet wouldnít fire. Hereís my logic:

According to your explanation, the propellant wonít burn until it gets a source of outside oxygen. So in order to get this outside oxygen, the slug must first be expelled from the casing -- but it canít expel the slug until it gets access to outside oxygen. Youíve set up a paradox whereby the bullet cannot muster enough power to fire until it actually fires. That just doesnít make sense.

Any munitions experts care to weigh in?

Also,the propellant doesn't actually explode, it just burns very fast.

An explosion (excepting a nuclear explosion, of course) is just an extremely rapid burning in a confined space. Too much pressure builds up during the burn and voilŠ! You have an explosion. So the only difference between burning and exploding lies only in how fast the burn happens and whether it does so in a confined space.

~ Complacency is far more dangerous than outrage

05-13-1999, 10:27 AM
I am not a munitions expert, but i don't think that it would fire. It would be my understanding that in the begining, the oxygen it the case is used. This is not the end of the rapidly burning\explosion reaction. The process continues while the bullet travels down the barrel and has enough extra to shoot flames out of the end of the barrel. Oxygen would have to be present this entire time. Even if there was enough oxygen in the case, they would be spread out over the length of the barrel and not it the small area that they started. My predition would be that the the bullet would stop not long after hitting the lans.

05-13-1999, 05:41 PM
Wow! we got some good info on both sides... Maybe we should call NASA and tell them to add one more experiment on their next trip...

On the side, anyone care to test the underwater one? I thought about it more and maybe you have some ideas. If a gun was able to fire a bullet underwater then why swim around with the 'ol trusty spear gun? Wouldnt it be better to Leathal Weapon you way out of a shark attack with a pair of 9 millimeter Berrettas?

I just though that if a gun can fire in space it should also fire underwater... however the bullet wouldnt travel far, if at all making guns useless against Jaws. There are strata? in a guns barrel that dig lines in the soft metal of the bullet causing it to spin for more accuracy and distance, like how you throw a football. I am not an expert on hydraulics but you cant compress liquid.. when I think of a bullet travelling at a high speed I cant see the water getting out of the way fast enough, and how the bullet would be sucking water in its wake on the way out... without testing it firsthand, all you can do is theorize what might happen anyway. So in answer to the question my opinion (not fact) is yes, a gun will fire in space and underwater but only in space would a bullet travel enough to be of any use.

Anyone want to try that experiment?

05-13-1999, 06:03 PM
We'll do this in no particular order.

Gunpowder does not require external oxygen to ignite, nor does TNT or nitroglycerine (which, I believe, actually produces oxygen when ignited). Gunpowder would light just fine in a vacuum. Gunpowder will also work just fine underwater, as long as the powder itself is kept dry.

There are two definitions of what an explosion is. An explosion is commonly defined as a rapid expansion of gasses due to a chemical reaction. This would include gunpowder explosions, gas, diesel fuel (when under the pressure present in an internal combustion engine), hydrogen, etc. In the explosives field, an explosion is defined as a rapid expansion of gasses due to a *self contained* chemical reaction. Of the above examples, only gunpowder qualifies.

There are a great number of combustion reactions which meet the common requirements for what an explosion is.

I'm almost certain that magnesium flares contain their own oxydizers. Pure magnesium doesn't burn that well in air, except in powdered form. I doubt it would even light in water.

Oxidants are not defined as oxygen containing compounds. Oxidants are substances which remove electrons from (oxydize) other substances. Oxygen is the most familiar of these substances.

-Bob

05-13-1999, 09:15 PM
Guns can fire underwater for the same reason they can fire in space (cartridge is self-contained), but the underwater case is far more complicated - water is far more viscous than air or vacuum, and offers more resistance.

If the hammer/firing pin does not strike well enough, the primer won't be fired.

A longish barrel filled with water is trouble, too (may burst).

Even if the bullet fires successfully, bullets depend on moving very fast to do their damage. The faster you move, the more the resistance of the water, the faster you slow down. Thus, a relatively low velocity projectile with greater mass and a killing shape is a more practical underwater weapon -- accounting for the popularity of the speargun.

05-14-1999, 12:47 AM
Gunpowder (at least the "black powder" type; I'm not absolutely certain what's inside a modern rifle bullet is the same) is make of mostly potassium nitrate with some carbon and a little sulfur.

The potassium nitrate is there as an oxidant. I'm pretty sure that anything which requires external oxygen to sustain combustion won't explode, it'll just burn.

05-15-1999, 12:56 AM
- - - A bullet doesn't need any more air to fire than what's inside the cartridge. At no time does it have to suck in any air. The real question here is "If you took a firearm out to space, would the cartridge seal well enough to hold the air inside necessary to fire?"
**********************************
- I just remembered, -
I think caseless ammunition might do it, just as it is. $2200 rifle though, and $11 a shot. Kinda pricy. ------ search " Voere of Austria + Heckler and Koch".
********************************** - MC

05-19-1999, 02:11 AM
Devilfish is right. As a terrible tot I personally blew up a pitcher of Kool-Aid with an M-80..very devilish plot, I lit the M-80, everyone ran away, then I tossed the M-80 in the Kool-Aid pitcher, everyone thought it was extinguished, gave a sigh of relief. Then the pitcher blew up pelting everyone with plastic shards and cherry Kool-Aid. You bet I knew the Kool-Aid wasn't going to put out the fuse.
Lazy fishermen have been known to use explosives as well. Not a very sporting way to collect crappies.

05-19-1999, 04:42 AM
Guns will fire in a vacuum. The Army has done experiments on this an show it to be true. The problem is heat dissapation. The only way for heat to dissipate in a vacuum is radiation. Fire more than one or two shots and the gun will be so warped that the bullet won't escape the muzzle and the gun will explode. Supposedly there are designs for guns with special cooling systems and big radiation fins for use is space (in fact there are guns designed like that for military use now, most vehicle mounted macine guns are like that).

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Jim Petty
A Snappy message should appear here

05-23-1999, 08:41 PM
I was recently talking with my father about this thread, and he had an interesting take on underwater gun firings:

He suggests that the viscosity of water might slow down the firing pin to the point where it will strike the primer-containing casing with insufficient force to start the reaction. This may be what jens was referring to above, but Iím not sure.

If the firing pin does indeed strike hard enough, he votes for a successful Ė albeit fairly slow and short-lived Ė underwater firing.


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~ Complacency is far more dangerous than outrage ~

05-23-1999, 10:15 PM
Torq is correct. Gunpowder contains all the oxygen it needs for combustion in the form of nitre, that is, potassium nitrate (or saltpetre) - KNO3. I'm sure a fair amount of ambient oxygen is incorporated into the muzzle flash of a conventional firearm, but compare a bullet cartridge to a pipe bomb, and you'll see that by the time the combustion has access to the atmosphere, a fair amount of oxidation has already taken place. This is the beauty of gunpowder - it does not have to rely on ambient oxygen.
As for firing a gun underwater - BLAMMO - yer gonna have a facefull of shrapnel, boys. Hydraulics being what they are, something's got to give - and it's not going to be the water, it's going to be your firing chamber or gun barrel. The force required to move that much water that quickly is much greater than any conventional firearm's construction can withstand. And if you think the "air cushion" in the barrel trick is going to work, I suggest you test it out by holding the muzzle of a 12-gauge shotgun in the water in that thar horse trough and tell us what happens. When you get back from the hospital.

05-23-1999, 10:52 PM
Sidelight on firing guns in space-
I was obliquely involved in "Star wars" experiments performed at Arnold AFB, Tullahoma, TN during the mid-80's. They were developing a satellite-destroying weapon, a vacuum gun, if you will. A charge (top secret explosive, I didn't ask) was placed into a firing chamber behind a uranium pellet the size of a bb encased in some relatively soft plastic. ("Bullet" diameter .750"). The bullet was fired down a very long gun barrel (120 feet, manufactured in sections, which is how I got involved) at about 4,000 fps into a vacuum tunnel underground. At the muzzle, a "stripper" arrangement pulled the plastic away from the pellet which continued its flight down the tunnel (it was a "scientific grade" vacuum pulled in there) about 1/4 mile, where it met its target. I was told they could vaporize a cubic foot of steel by this method. (Seems to me they were planning for much "harder" targets than some rickety satellites, but who knew what the Russkies had up their sleeves at that point?)

05-24-1999, 12:29 AM
Want to do a fun little prank and, if you're lucky, do a few trillion dollars worth of damage in the process?

Take a large hollow satellite or two, fill them with ball bearings and put them into retrograde orbit at the same height as geosyncronous orbit. For maximum effect have the satellites open up release their cargo. Being in opposite orbits, the ball bearings and communications satellites will collide at thousands of miles an hour destroying the satellites, knocking the ball bearings into lower orbits and creating millions of pieces of space junk floating around.

In 12 hours you could set the entire long distance system back 40 years. In a month or so you could take out every satellite in orbit (excepting a few that orbit in very high orbits). Imagine--No cable TV, no cellular phones, no GPS or Loran navigation, no spy satellites, no manned space missions and many more practical benefits. And even better, you will have killed any chance of them for tens of thousands of year.

Plus, you will create a ring system around the planet that will temporarily be as impressive as Neptune's or Jupiter's. It won't be stable because particles will be traveling in opposite directions, but that will lead to beautiful meteor showers.

Just keep two thoughts in mind if trying this--
1) Putting things in retrograde orbit is more difficult and expensive than in prograde orbit.
2) Don't mention my name.


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Jim Petty
A Snappy message should appear here

06-01-1999, 11:32 AM
>>As to your second question, shooting a gun under water isnít much different than shooting on land.

quote:
------------------------------------------------------------------------
the water in the barrel of the gun would block the bullet causing the gun to explode
------------------------------------------------------------------------


No more than the air in the barrel would block a bullet; the bullet has to travel through the medium of water just as it has to travel through the medium of air, pushing either medium aside as it goes. But water is thousands of times more dense than air, so the bullet would travel much slower and be stopped much sooner. Of course, if you went very, very deep into the ocean, I suppose you might get to a depth where the pressure of the water is so great that it would be easier for the barrel to explode than it would be to expel the bullet into that great pressure (of course, by that pressure, the gun -- not to mention you -- would probably be crushed, so itís a moot point anyway).>>

Wrong on several levels. Air is compressible, and thus relatively easy to drive out in front of the bullet. The amount of water held in the grooves of rifling is capable of wrecking many smaller bore rifles.

A firearm would not be damaged by high water pressure -except the cartridges loaded in it.

The water pressure is roughly even in all directs, so there would be no point where it was "easier" to burst the barrel due to it.

whatthefee
05-11-2012, 09:41 PM
People on the internet used to be so nice and civilized

drewtwo99
05-11-2012, 09:47 PM
Can zombies survive in a vacuum? If so, I'm glad my guns work in vacuums.

whatthefee
05-11-2012, 09:54 PM
That's a relief

buddha_david
05-11-2012, 09:55 PM
Can zombies survive in a vacuum?
Apparently not, judging by the (lack of) usernames. What's up with that?

Gagundathar
05-11-2012, 09:55 PM
That was quite interesting. Like a jaunt into another dimension where posters with no names converse calmly and rationally without resorting to crass behavior.

Did Mr. Peabody engage the wayback machine?

whatthefee
05-11-2012, 09:59 PM
Apparently not, judging by the (lack of) usernames. What's up with that?

That would be because this thread was started in 1999

GreasyJack
05-11-2012, 10:03 PM
Surely we must have had a real gunfight on the moon by now.

zoid
05-11-2012, 10:10 PM
That would be because this thread was started in 1999

You knew that and decided to resurrect it anyway? :dubious:

You chose...
poorly

johnpost
05-11-2012, 10:10 PM
Apparently not, judging by the (lack of) usernames. What's up with that?

zombie or no

people were really shy back then.

or there really a lot of nameless, faceless people.

computer database burp.

whatthefee
05-11-2012, 10:12 PM
You knew that and decided to resurrect it anyway? :dubious:

You chose...
poorly

I was interested in how civilized the internet used to be, compared to nowadays with all the "trolls" and what not.