Pistol Shot Captured At 73,000 Frames Per Second - Super Slow Mo!

[DougGuy]

Mythbusters Adam Savage is nearly rendered speechless by incredible slomo footage that captures a bullet being fired at 73,000 frames per second. Shot at these speeds, the video reveals a dance of pressure and fire that would otherwise be missed by the unaided eye.


https://www.youtube.com/watch?v=7y9apnbI6GA


https://www.youtube.com/watch?v=7y9apnbI6GA&feature=player_detailpage

[jeepyj]

That's incredible! Thanks for sharing.
jeepyj

[MrWolf]

Pretty impressive! Thanks.

[historicfirearms]

It is interesting to see the small cloud in front of the bullet. I didn't expect that and wonder what it is from.

[Tom Myers]

For what it's worth, my guess would be that the small cloud surrounding the bullet would be the air that was in the barrel ahead of the bullet.

[osteodoc08]

Impressive to say the least. I'd love to see them use a rifle and crank up the velocity

[Ballistics in Scotland]

It is indeed a marvelous achievement. A world exclusive? It has certainly been done before, and shows nothing that wasn't already known.

A small, usually trivial amount of the combustion gases do escape past the bullet, partly before it engages in the rifling, but perhaps also to some extent as the bullet goes down the barrel. As they are initially at very high pressure, and are almost perfectly elastic, they at first outdistance the bullet. But being so light, they decelerate and are soon passed.

In most powders there is a surplus of combustible material over oxygen, and in the bore they don't burn. Military ammunition designers try to minimize this. But on contact with atmospheric oxygen they flash.

[Bzcraig]

Very cool indeed! Would love to see rifle and shotgun too

[popper]

Pressure cloud after the bullet leaves is interesting as are the large particles in the cloud.

[BrentD]

Notice how the recoil doesn't even begin to start until the bullet is well clear of the barrel? I'm not sure I understand that at all.

[M-Tecs]

On firing I believe you will get some initial blow by until the bullet fully engages the barrel.

https://www.youtube.com/watch?v=otpFNL3yem4

The barrel flex on rifles is impressive in slow mo.

https://www.youtube.com/watch?v=HGivoWD9OvQ

https://www.youtube.com/watch?v=cpTzr4yZvtc

[KenH]

It would be neat to see a Paper Patched bullet fired - but the patch might stay on too long and be completely out of frame before dropping away from bullet?

Thanks for the link.

[BrentD]

Ask and you shall receive


https://www.youtube.com/watch?v=TCJnYh9UVMg

[M-Tecs]

Ask and you shall receive


https://www.youtube.com/watch?v=TCJnYh9UVMg

OK how do I post tubes so it is more than a link? Thanks

[BrentD]

OK how do I post tubes so it is more than a link? Thanks

Use the Insert Video button, second from the right on the tool bar on top of the reply window. It's between the "insert image" button and the "quote"

[DougGuy]

I think that initial cloud is more moisture in the ambient air in the barrel which is condensing due to the rise in pressure in the barrel from the bullet moving. It could be some gas escaping but one would think that if it was gas escaping, it would be coming much more rapidly than that lazy looking little cloud.

To get the video to play in the thread, I went to youtube and instead of copying the url from the page or the location bar, I simply right clicked in the video and chose "copy video URL" then come to this forum, choose the Insert Video button above, and paste into the dialog box that opens. Every other way I tried to do it would only paste a link into my post.

[DougGuy]

Let me see if I can get the vids to play...



The following errors occurred with your submission

You have included a total of 3 videos in your message. The maximum number that you may include is 1. Please correct the problem and then continue again.

The use of videos is subject to them being enabled by the administrator.




[QUOTE=M-Tecs;3349370]On firing I believe you will get some initial blow by until the bullet fully engages the barrel.


https://www.youtube.com/watch?v=otpFNL3yem4&feature=player_detailpage

[M-Tecs]

Use the Insert Video button, second from the right on the tool bar on top of the reply window. It's between the "insert image" button and the "quote"

Wow that's easy when you know where to look. Thanks!!!!!!!!!!!!!

[DougGuy]

Try the second one:





The barrel flex on rifles is impressive in slow mo.


https://www.youtube.com/watch?v=HGivoWD9OvQ&feature=player_detailpage

[DougGuy]

And the third:






https://www.youtube.com/watch?v=cpTzr4yZvtc&feature=player_detailpage

[BrentD]

Condensation happens when pressure drops, not when it rises.

[Ballistics in Scotland]

It is reduction, not increase in pressure that causes condensation, aircraft wingtip contrails being a prime example. A good deal of water vapour is produced by the combustion of smokeless powder, just like most other internal combustion engines.

I suppose this happens as the bore pressure is released, but I doubt it, as the temperature of the gases would still be far above the boiling point of water. It should be verifiable by finding out what happens with black powder, which should produce no water vapour.

[DougGuy]

Notice how the recoil doesn't even begin to start until the bullet is well clear of the barrel? I'm not sure I understand that at all.



In a typical .45 caliber 1911, the bullet/boolit is about 4' in front of the muzzle when the slide begins it's rearward travel. I think JMB called it "delayed blowback" if I am saying this correctly.

[BrentD]

Black powder burns hydrocarbons (charcoal) , so water is going to be a byproduct there too.

Whatever was in front of that bullet is hard to say. Blowby is my best guess.

[Ballistics in Scotland]

Let me see if I can get the vids to play...
[/LIST]



[QUOTE=M-Tecs;3349370]On firing I believe you will get some initial blow by until the bullet fully engages the barrel.

#


Those gases were certainly ahead of the bullet in the bore.

Video of this type demands some pretty sophisticated equipment, but still pictures of bullets are within anybody's grasp at relatively modest investment, using triggering devices such as the Camera Axe.

http://www.cameraaxe.com/

[popper]

The 'puff' in front is compressed air (plus junk left over) from the bore. Note it is overtaken by fired gasses so not much velocity/energy in it. Air is compressed by motion, then pressure released at muzzle, could be condensation or steam for collision with moist air. Glowing particles in the gas stream maybe unburnt powder or just hot junk from the primer - looks similar to primer test vids. Unlocking is what should be, only unlocks when pressure drops - controlled by friction of the barrel locking lug/spring pressure/bolt weight. Otherwise you have a 'bullet' going the same speed in both directions.

[Harter66]

In the 1st video did you notice that the bullet is tipped?

I love the slow mo videos there is so much to observe that can be altered tweaked and adjusted in the loads.

[Hawks Feather]

Thanks for sharing that video. It is pretty impressive to watch.

[Walkingwolf]

During the initial ignition the bullet is not sealed to the lead/chamber. It is the same way a airsoft GBB works, a small portion of gas is allowed to pass by valve before it can close. Probably the gas checking is lowered by using soft lead hollow base bullets, most bullets currently being used are hard cast, or jacketed. From what I see in the video the gasses exiting look more like burning gasses than vapor. If I fire one of my CO2 pistols with no BB I will get a small puff of white vapor, and in the video it is not white.

[Red River Rick]

This is probably the best video out there:

https://www.youtube.com/watch?v=QfDoQwIAaXg

At approximately 2:30, it shows some det cord and a piece of "Shaped Charge" (for cutting steel) detonating.

RRR

[popper]

The PP one shows really good boolit wobble as the patch comes off.

[Schrag4]

I started it over and over right where the slo-mo starts. It seems clear to me that the recoil starts well before the bullet exits the barrel.

[Echo]

For what it's worth, my guess would be that the small cloud surrounding the bullet would be the air that was in the barrel ahead of the bullet.

Compressed by advancing bullet, expanding when it reaches the muzzle - or maybe minimal blow-by...

[rondog]

This is probably the best video out there:

https://www.youtube.com/watch?v=QfDoQwIAaXg

At approximately 2:30, it shows some det cord and a piece of "Shaped Charge" (for cutting steel) detonating.

RRR
Thanks for posting that, now I don't have to! I agree it's probably the best slo-mo video on the 'net! Been loving that one for years. Same guy has other very good ones, but seem to be tougher to find. I watched a few once that showed lots of guns firing, even several rigged to blow up when fired. Those were scary. Haven't found them since.

[waksupi]

I started it over and over right where the slo-mo starts. It seems clear to me that the recoil starts well before the bullet exits the barrel.


If it didn't, there would be nothing driving the projectile.

[M-Tecs]

At 11 seconds you can see the gas leakage at the breech. I do think some of the muzzle plum is gas flowing around the bullet before the bullet fully engages the bore.

[DougGuy]

I started it over and over right where the slo-mo starts. It seems clear to me that the recoil starts well before the bullet exits the barrel.

Recoil starts the instant pressure is built inside the case. Slide movement -other than- the gun moving in the shooter's hands reacting to pulling the trigger doesn't occur until the bullet/boolit is well clear of the muzzle.

[Ballistics in Scotland]

Black powder burns hydrocarbons (charcoal) , so water is going to be a byproduct there too.

Whatever was in front of that bullet is hard to say. Blowby is my best guess.

The usual formula for the combustion of black powder is:

10KNO3 + 3S + 8C = 3K2SO4 + 2K2CO3 + 6CO2 + 5N2
It isn't the full story, though. There is nothing in the formula to explain the smell. People who try to make gunpowder with pure carbon - it is a pity, since lamp black is available very finely divided - are sadly disappointed. We know too that charcoal produced at low temperatures, and slightly brown, ignites at lower temperature than the common black variety. I don't believe it affects the total energy
content, once ignited, much if at all.

Clearly there is something else there, and my guess is that it puts the powder a little in the direction of smokeless, by putting oxygen and combustible material in one molecule. The reasons I doubt if it produces much water are that there is very little of it, and that even the extra substance contains carbon to oxidise into carbon monoxide and dioxide too.

So I still think blowby of combustion gases are the most likely source of that little cloud.

[35remington]

Actually the slide, locked to the barrel, starts moving almost immediately and is in considerable rearward motion well before the bullet leaves the barrel. This is how it is supposed to work.

The slide does not unlock from the barrel until the bullet is gone. This is why spring strength has no bearing on when the gun unlocks.

[35remington]

Since the gasses preceding the bullet are not confined, the pressure that expands them is relatively low and the velocity they attain is modest, barely preceding the bullet. Note the gasses following the bullet rocket past it once freed.

A matter of pressure. The gas that you see is indeed that which leaked past the bullet on its trip down the barrel.