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12/6/2019 7:27:02 PM
Posted: 3/14/2011 3:30:12 PM EST
I know this is a crazy question but I was wonder which contributes more to the heating of the barrel: the hot gases from the gunpowder or the friction of the bullet going down the barrel?

I realize both are factors but any idea as to how they contribute to the total heat, percentage wise?
Link Posted: 3/14/2011 3:48:20 PM EST
I would think the hot gasses and pressure from it account for most of the heat...
Link Posted: 3/14/2011 4:18:11 PM EST
I couldn't figure out how much but I'd say the major percentage would be from friction. Think about it, the burning propellant in the barrel is only there for a fraction of a second. For a fraction of a second you could pinch a candle and put it out without burning your fingers. But say take your finger and touch a car tire that is going 50 miles per hour and you'll burn instantly. I know it's not an apple to apple comparison but you get the picture.

Link Posted: 3/14/2011 4:51:52 PM EST
i'd say both, but mostly from hot gas.
Link Posted: 3/14/2011 4:52:26 PM EST
I've been told it's the friction that accounts for most of it.
Link Posted: 3/14/2011 4:57:15 PM EST
I'm voting for the 50,000 psi scorching hot gasses personally. Think about how hot a piece of brass is immediatly after ejection even from a cold chamber. It certainly isn't hot from friction. THat hot gass rushing down the barrel may only be there for a fraction of a second, but it is at extraordinarily high pressure and that makes a big difference.

Adrock1
Link Posted: 3/14/2011 4:59:13 PM EST
Link Posted: 3/14/2011 5:44:12 PM EST
Originally Posted By ezlife45:
I couldn't figure out how much but I'd say the major percentage would be from friction. Think about it, the burning propellant in the barrel is only there for a fraction of a second. For a fraction of a second you could pinch a candle and put it out without burning your fingers. But say take your finger and touch a car tire that is going 50 miles per hour and you'll burn instantly. I know it's not an apple to apple comparison but you get the picture.



Candles don't explode with vicious force.
Link Posted: 3/14/2011 5:49:36 PM EST


Friction guys .....
Link Posted: 3/14/2011 5:56:18 PM EST
[Last Edit: 3/14/2011 5:59:24 PM EST by HeavyMetal]
Link Posted: 3/14/2011 5:56:34 PM EST
Originally Posted By HeavyMetal:
Gas cutting like a torch. If it were friction, it would be higher toward the muzzle. The barrel wears from the throat.


Agree

Link Posted: 3/14/2011 5:58:48 PM EST
I searched around and found my answer from some government tests on the .30-06:

ENERGY CONSUMED IN FIRING
EventCaloriesPercent
heat to cartridge case 131.0 calories 4.26 %
kinetic energy of bullet 885.3 calories 28.78 %
kinetic energy of gases 569.1 calories 18.50 %
heat to barrel 679.9 calories 22.10 %
heat to gases 598.6 calories 19.46 %
heat generated by friction 212.0 calories 6.89 %
Total3075.9 calories

so the ratio of gas to friction heating of the barrel is: 3.2.
Link Posted: 3/14/2011 6:21:43 PM EST
Originally Posted By HeavyMetal:
So, does friction cause gas port erosion too?

Gas checking or gas cutting.

Crappy pic showing gas port erosion:

http://www.ar15barrels.com/tech/gas-port-erosion.jpg

Crappy or not. That is a great image

Link Posted: 3/15/2011 5:03:57 AM EST
Originally Posted By HeavyMetal:
So, does friction cause gas port erosion too?

Gas checking or gas cutting.

Crappy pic showing gas port erosion:

http://www.ar15barrels.com/tech/gas-port-erosion.jpg


There is something wrong with this picture. Gas port erosion usually creates an hour glass pattern as the gas port erodes. The barrel in the picture looks like it would have been ripping the jackets off the projectile...
Link Posted: 3/15/2011 11:57:31 AM EST
Shotgun barrels get extremely hot, and I would presume a plastic wad to go down a smoothbore barrel with less friction than a copper-jacketed bullet through a rifled barrel.

So I'll go with hot gasses.
Link Posted: 3/15/2011 12:44:54 PM EST
Originally Posted By strat81:
Shotgun barrels get extremely hot, and I would presume a plastic wad to go down a smoothbore barrel with less friction than a copper-jacketed bullet through a rifled barrel.

So I'll go with hot gasses.


winner

good point.
Link Posted: 3/15/2011 12:54:05 PM EST
Global Warming.
Link Posted: 3/15/2011 1:10:48 PM EST
How hot do barrels get when firing blanks?
Link Posted: 3/15/2011 2:03:09 PM EST
Ask Al Pachino when he was filming, "Scarface".
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