How HOT is a bullet in flight?
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CoRoMo
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I've always wondered what the peak temperature is inside the shell at the point of ignition. Anyone ever heard of that for any certain cartridge?
Stirling XD
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I don't know what the exact temerature is, but my experience is that its hot enough to burn flesh.
Several years ago my dad and I were at the county sheriffs shooting range as part of our qualification for our CCP. My dad was on my left and we were shooting at silhouette at abour 12 feet. The targets were in metal frames that were just a little bigger then the targets themselves. The instructor had us shooting with our elbows at our sides and both hands holding the gun so that our arms formed a triangle. (I'm sure there is a name for that but I'm not sure what it is.) There were at least 15 people shooting that day. During one of our shooting exercises, I felt something hit my arm. That was followed by a sharp burning sensation and I immediately started flailing my arm to get off. Out of the corner of my eye, I saw my dad doing the same thing. I looked on the ground to see what it was and saw a shiny piece of lead.
All of the flailing got the instructors attention and he walked over to investigate. We concluded that someone had shot the metal frame of the target holder and dad and I caught the ricochet. The bullet that hit dad actually broke the skin enough to draw blood. At the time, I assumed the culprit was the guy on my right, but I guess it could have been someone else down the line. But that bullet felt just as hot or hotter then an ejected casing. I remember being amazed that a bullet would ricochet at that sharp of an angle. ALWAYS wear your safety glasses.
Several years ago my dad and I were at the county sheriffs shooting range as part of our qualification for our CCP. My dad was on my left and we were shooting at silhouette at abour 12 feet. The targets were in metal frames that were just a little bigger then the targets themselves. The instructor had us shooting with our elbows at our sides and both hands holding the gun so that our arms formed a triangle. (I'm sure there is a name for that but I'm not sure what it is.) There were at least 15 people shooting that day. During one of our shooting exercises, I felt something hit my arm. That was followed by a sharp burning sensation and I immediately started flailing my arm to get off. Out of the corner of my eye, I saw my dad doing the same thing. I looked on the ground to see what it was and saw a shiny piece of lead.
All of the flailing got the instructors attention and he walked over to investigate. We concluded that someone had shot the metal frame of the target holder and dad and I caught the ricochet. The bullet that hit dad actually broke the skin enough to draw blood. At the time, I assumed the culprit was the guy on my right, but I guess it could have been someone else down the line. But that bullet felt just as hot or hotter then an ejected casing. I remember being amazed that a bullet would ricochet at that sharp of an angle. ALWAYS wear your safety glasses.
Hungry Seagull
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All I know is after 30 rounds slow fire, my shotgun barrel radiates much heat. Too hot to touch for about 20 minutes after. I cannot imagine what temperature those short mag slugs will be at.
Cyclimus
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There's a simple test you could do to figure this out. All matter has a temperature coefficient that specifies how quickly it dissipates heat, etc. (mind you all, thermodynamics was 8 years ago and I am not a thermal engineer so I use this stuff very very sporadically). The simplest method of testing the temperature of a bullet in flight is to actually capture it mid-flight. The method for doing this is to use a water chamber. Here's how this actually works out awesome:
Since we know the temperature coefficient for water, all we have to do is fire the round into the water from the desired ranges and monitor the temperature shift in the water itself. Then with a little mass/time/temperature calculations we can solve for the actual temperature of the bullet on impact. I'm at work so I don't have my equations here with me, but that's the simplest, safest and most reliable test. This also allows for the bullet to fragment, expand, etc as it is designed to do so that energy transfer is included in the temperature shift of the water itself.
Don't overthink it.. it's pretty simple thermodynamics and physics.
Since we know the temperature coefficient for water, all we have to do is fire the round into the water from the desired ranges and monitor the temperature shift in the water itself. Then with a little mass/time/temperature calculations we can solve for the actual temperature of the bullet on impact. I'm at work so I don't have my equations here with me, but that's the simplest, safest and most reliable test. This also allows for the bullet to fragment, expand, etc as it is designed to do so that energy transfer is included in the temperature shift of the water itself.
Don't overthink it.. it's pretty simple thermodynamics and physics.
The kinetic energy of a moving bullet is converted to heat when the bullet is stopped abruptly.
That is how an armor piercing bullet penetrates thin armor. The bullet strikes the armor and the heat melts the steel, allowing the carbide core to penetrate. If the armor is too think, the surface will still melt but the heat will dissipate too fast for the interior of the armor to soften. But the AP core will often stick in the armor, welded in by the molten metal.
Another phenomena resulting from bullet energy turning to heat is the bulged barrel. When a bullet moving in the barrel encounters an obstruction, it stops, and its kinetic energy turns to heat, softening the barrel metal enough for it to bulge or split from the pressure.
Jim
That is how an armor piercing bullet penetrates thin armor. The bullet strikes the armor and the heat melts the steel, allowing the carbide core to penetrate. If the armor is too think, the surface will still melt but the heat will dissipate too fast for the interior of the armor to soften. But the AP core will often stick in the armor, welded in by the molten metal.
Another phenomena resulting from bullet energy turning to heat is the bulged barrel. When a bullet moving in the barrel encounters an obstruction, it stops, and its kinetic energy turns to heat, softening the barrel metal enough for it to bulge or split from the pressure.
Jim
Fred Fuller
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Ever seen a thin-jacketed varmint bullet fired at a velocity higher than it was designed to handle disintegrate in flight? Try loading bullets made for the .22 Hornet in a higher velocity .22 centerfire.
Hint- the biggest sign you're overdriving bullets is a blue-gray puff downrange when they come apart in flight. I've seen it theorized in writing that such bullets are basically just little copper bottles of molten lead when in flight.
From Sierra, regarding their 'Blitz' bullet for the Hornet: "You may want to avoid the Blitz bullets for the larger cases like the .22-250 and the .220 Swift, or fast (1x7" thru 1x9") twist barrels. Either of these may cause the Blitz's thin jacket to disintegrate in flight." - http://www.sierrabullets.com/index.cfm?section=techservice&page=xring&volume=2&issue=1
lpl
Hint- the biggest sign you're overdriving bullets is a blue-gray puff downrange when they come apart in flight. I've seen it theorized in writing that such bullets are basically just little copper bottles of molten lead when in flight.
From Sierra, regarding their 'Blitz' bullet for the Hornet: "You may want to avoid the Blitz bullets for the larger cases like the .22-250 and the .220 Swift, or fast (1x7" thru 1x9") twist barrels. Either of these may cause the Blitz's thin jacket to disintegrate in flight." - http://www.sierrabullets.com/index.cfm?section=techservice&page=xring&volume=2&issue=1
lpl
robsc
Member
Someone is getting stimulus money to conduct a research on the body odor of pigs. How much money could I get to conduct a reseach on the temperature of bullets after being fired?
Jon_Snow
Member
Shockwaves cause a temperature increase
Another thing to note is that the air crossing the shockwave created slightly ahead of a supersonic body is heated significantly. Air crossing a Mach 3 shockwave (roughly 3300 fps) jumps up by a factor of about 2.68, in Kelvin. So 85 deg F air going into the shock comes out at 1,002 deg F. Pretty damn hot. Now this assumes a normal shock, ie. that the shockwave is flat and perpendicular to the bullet path, which it isn't. Bullets create an oblique shock, which is has a smaller effect on the temperature, but it's still significant. For a bullet with a 40 deg angle on the nose the temp increase is still 2.00, so 85 deg air becomes 631 deg.
(For non-engineers; how 85 times 2.68 equals 998.3)
85 def F = (303 deg Kelvin)*2.68 = 812 deg Kelvin = 1,002 deg F
Another thing to note is that the air crossing the shockwave created slightly ahead of a supersonic body is heated significantly. Air crossing a Mach 3 shockwave (roughly 3300 fps) jumps up by a factor of about 2.68, in Kelvin. So 85 deg F air going into the shock comes out at 1,002 deg F. Pretty damn hot. Now this assumes a normal shock, ie. that the shockwave is flat and perpendicular to the bullet path, which it isn't. Bullets create an oblique shock, which is has a smaller effect on the temperature, but it's still significant. For a bullet with a 40 deg angle on the nose the temp increase is still 2.00, so 85 deg air becomes 631 deg.
(For non-engineers; how 85 times 2.68 equals 998.3)
85 def F = (303 deg Kelvin)*2.68 = 812 deg Kelvin = 1,002 deg F
Pistol bullets made of solid lead have to have a copper base if they are fired at magnum velocities because the lead will melt from the firing gases. Lead bullets fired from center fire cartridges will melt before impact. Gas temps in the thousands of degrees, tight fit in barrel, (i.e. friction) can raise temps in a bullet to several hundred degrees. Air cooling is not a factor because the bullet is in the air for fractions of a second.
Fact is folks, THEY GETS HOT.
Fact is folks, THEY GETS HOT.
1858rem
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lets put them to work on it!
Cannonball888
Member
That's interesting. Lead doesn't glow even when it's molten.
Hud
Member
CAUTION! Bullets exiting this firearm are EXTREMELY HOT and may cause burns.
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Cannonball888
Member
Nice Hud. Is that real? Must be the copper jacket. So, why are bullets never glowing in other photos?
1858rem
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to quote Cannonball888 - That's interesting. Lead doesn't glow even when it's molten.-
when im casting, if there is only a little led in the pot i can turn it pretty darn red so what do you mean doesnt glow?
when im casting, if there is only a little led in the pot i can turn it pretty darn red so what do you mean doesnt glow?
Cannonball888
Member
I've just never seen molten lead glow. With just a little in the pot, do you think it might be showing the glowing iron underneath?
1858rem
Member
crossed my mind, didnt think lead was transparent though.....maybe a reflection off the surface?
1858rem
Member
huds pic kinda looks like hot gas exiting around the bullet but the bullet seems to glow a little too, very cool pic though!
I can't remember, but it's possible that the bullets we were using were copper plated/jacketed.
It may be difficult to capture the glow with a camera as you need to shine a lot of light on the bullet for high speed snap shots. Maybe it is particular to .22 bullets (small enough mass, fast enough to pick up some heat from friction, slow enough to see.) Maybe I was seeing things.
I'll have to try it again some time.Guns and more
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I'll add the fact that the bullet has been hammered by the explosion, and followed by fire for a period of time. The air in the chamber has been rapidly compressed with the detonation so it too is superheated.
I know the casing that went down my shirt one time was damn hot.
Vincent di Maio cited some tests that proved that bullets are not hot enough to be sterilized by firing.
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