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Discussion Starter · #21 ·

This is just a cool slo-mo pic :cool:


Burn time? Short!
That little puff before the bullet leaves the barrel...

I've always thought that when the powder STARTS to burn and has made
enough pressure to unseat the bullet, the pullet would pop out of the case
and STOP at the forcing cone (revolver) or when it meets the lands (auto)
until pressure goes high enough to force the bullet into the rifling.

Anyone who has ever slugged a barrel knows how much force that takes.

So in the GIF above there is that little puff of smoke coming out before the
bullet, which could be gasses leaking around the bullet as it is stuck on the
lands.

I can't think of any other explanation for that happening.
 

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That little puff before the bullet leaves the barrel...

...

So in the GIF above there is that little puff of smoke coming out before the
bullet, which could be gasses leaking around the bullet as it is stuck on the
lands.

I can't think of any other explanation for that happening.
Yes, it could be gasses leaking around but some is also likely to include:

- gilding, oil, steel, water, etc being pushed ahead of the bullet

... and suddenly cooling once out of the confines of the barrel, thus condensing.
 

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Discussion Starter · #23 ·
Possible?
But all the heat (plasma) is behind the bullet.
Not in front of it.
Friction heat does not get that hot!
 

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I've always read there are several things going on once the primer ignites the charge. First the expanding gases unseat the bullet. Depending on the length of the bullet the bullet may not completely exit the case before contacting the lands or even the forcing cone (however I feel this is unlikely). Next is once the bullet engages the lands and exits the case the gases fill the chamber. With revolvers once the bullet exits the case and starts into the forcing cone you have the barrel gap. In a semi-automatic such as the 1911, the slide starts back extracting the empty case. With cast bullets the base of the bullet will expand filling the grooves. If the bullet is too hard or undersized the bullet will not fill the grooves allowing hot gases to force their way around the bullet as it travels down the barrel.

So to keep the hot gases where they should be, behind the bullet, there are several things that must happen almost instantly. I may have forgotten some things and very well could have misunderstood others, if I am wrong here please correct me.

My $0.02 plus tax,
Grumpy
 

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Possible?
But all the heat (plasma) is behind the bullet.
Not in front of it.
Friction heat does not get that hot!
Yes I think that it is safe to say that some of the gas gets out in front of the bullet before it contacts with the actual rifled bore of the gun, transiting the lead of the chamber. And of course with revolvers you also have bleed off between the barrel cylinder gap. Then you get into "gas guns" and all that entails.
 

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There is air in the barrel ahead of the bullet that is getting pushed and compressed by the rapid acceleration of the bullet.

Contrails come from the exhaust of jets engines. Could part of what we see at the gun muzzle ahead of the bullet result from the rapidly heated air in the barrel (making it hot) striking the relatively cold open atmosphere?
 

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There is air in the barrel ahead of the bullet that is getting pushed and compressed by the rapid acceleration of the bullet.

Contrails come from the exhaust of jets engines. Could part of what we see at the gun muzzle ahead of the bullet result from the rapidly heated air in the barrel (making it hot) striking the relatively cold open atmosphere?
No doubt. The super slow motion videos show all sorts of things the human eye can not capture. They even show, what I believe to be, the pressure wave caused by the bullet's flight.

Grumpy
 
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Discussion Starter · #28 ·
No doubt. The super slow motion videos show all sorts of things the human eye can not capture. They even show, what I believe to be, the pressure wave caused by the bullet's flight.

Grumpy
Yes it does!
 

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There is air in the barrel ahead of the bullet that is getting pushed and compressed by the rapid acceleration of the bullet.

Contrails come from the exhaust of jets engines. Could part of what we see at the gun muzzle ahead of the bullet result from the rapidly heated air in the barrel (making it hot) striking the relatively cold open atmosphere?
Yes.
 

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There is air in the barrel ahead of the bullet that is getting pushed and compressed by the rapid acceleration of the bullet.

Contrails come from the exhaust of jets engines. Could part of what we see at the gun muzzle ahead of the bullet result from the rapidly heated air in the barrel (making it hot) striking the relatively cold open atmosphere?
They could be. But what kind of volume of air are you talking about? Additionally what affect would that actually have on the ballistics of the fired round?
 

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I doubt it would have any real affect on the ballistics. It's merely a thought as to some of what is seen exiting the muzzle ahead of the bullet.

It's a small volume, less than1 cubic inch for a 5" 45 barrel, but compressed in a micro-second, then released to the relatively cold air outside the muzzle.
 

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Discussion Starter · #32 ·
I doubt it would have any real affect on the ballistics. It's merely a thought as to some of what is seen exiting the muzzle ahead of the bullet.

It's a small volume, less than1 cubic inch for a 5" 45 barrel, but compressed in a micro-second, then released to the relatively cold air outside the muzzle.
If someone would do high speed photography - in Infra Red, we would probably have the answer to that.
 

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When they fill scuba tanks, the tanks are placed in water to dissipate the heat build-up. And that compressor is not compressing the air anywhere near the compression speed in a barrel.
 

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When they fill scuba tanks, the tanks are placed in water to dissipate the heat build-up. And that compressor is not compressing the air anywhere near the compression speed in a barrel.
... and decompression, proportionately [ or thereabouts ] intense.

The infra-red proposed in #32 would be really cool*, in showing the change in temp. Does infra-red film exist fast enough? other sensors? Being lower energy, that kind of speed seems, intuitively, more difficult. But maybe not.


*- yeah, I wrote it.
 

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Discussion Starter · #35 ·
Kodak has discontinued production of cut sheet high speed infra red film - due to declining demand.
35 mm is still available.
Digital high speed infrared photography seems to be the new normal.
Teledyne claims 29000 frames per second.
So maybe?
 

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Kodak has discontinued production of cut sheet high speed infra red film - due to declining demand.
35 mm is still available.
Digital high speed infrared photography seems to be the new normal.
Teledyne claims 29000 frames per second.
So maybe?
Wow! 29000 ... ~1,000x human vision. That oughta be good.
 

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Kodak has discontinued production of cut sheet high speed infra red film - due to declining demand.
35 mm is still available.
Digital high speed infrared photography seems to be the new normal.
Teledyne claims 29000 frames per second.
So maybe?
29,000 frames a second! You are kidding us right? 😳
 

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29,000 frames a second! You are kidding us right? 😳
'cavelamb' isn't:



Not sure about Teledyne.
 

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Teledyne was running over 20k frames per second before the 80's.
 

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Although interesting above my pay grade , Im still waiting fo the big Cheese to Chime in !
 
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