Bullet passing through ballistics gel - GIF

Bullet passing through ballistics gel.

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Previously:

https://www.homemadetools.net/forum/...002#post125307
https://www.homemadetools.net/forum/...880#post129305
https://www.homemadetools.net/forum/...765#post140113
https://www.homemadetools.net/forum/...354#post150620
https://www.homemadetools.net/forum/...107#post125853

I wonder what is causing the Flash and smoke? Never seen that in ballistic gel before. And why after the bullet exits the gel block?

As if the collapsing cavity triggered it somehow.

Could the bullet have been something akin to a tracer round that left some sort of residue that caused what looks like a small explosion?

I think that it may be caused by "dieseling" when oils in the gel are subject to intense pressure from the bullet and then there is an inrush of air and the oil and oxygen spontaneously combust. You can see this effect often with an air rifle fired in the dark without a pellet and you will see a flame out of the end of the barrel.
Oil and oxygen do not mix, hence why diesel engines do not need an igniter to run, only air pressure.

Could be dieseling.

Take a roll of masking tape into a DARK, NO LIGHT closet. As you PULL tape off the roll, watch closely where the glue releases from the roll. You will see a tiny line of light as the glue releases.

I wonder if something similar could be happening in the gel? The bullet ripped it apart so violently, then it came crashing back together and tried to bounce apart again. Perhaps the flash is a similar phenomenon, release of energy as the bonds are ripped apart?

Total speculation on my part..

Technically, all organic compounds are flammable. Ballistic gel is typically made from gelatin powder and water, and should not contain fat. As stated above, perhaps there was some lubricant on the bullet, or it may be that as the bullet passed through the gelatin (thereby creating a vacuum behind it), the low pressure "vacuum" extracted some fuel from the gelatin in gaseous form, and then, (as stated above) when the gelatin collapsed back together, created compression and diesel ignition. I'm sure not certain what the fuel source was.

People don't realize what compression you can get from a collapsing bubble. With a high power ultrasonic cleaner you can get a tiny bit of neutron radiation meaning the collapsing bubbles are causing fusion in like one atom at a time. Not exactly something you could power a city with, but shows the force of a collapsing vacuum bubble.

Copy and paste into wickapedia or Google

Sonoluminescence

Doesn't explain the smoke but interesting rabbit hole

Also
https://www.guns.com/news/2016/09/08...-testing-video