Eli5: why is impalement with rebar more survivable than a shot from a .50 BMG round?

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How is it that a bullet that is 12.7 mm in diameter can kill somebody with so much more bodily damage than a 20mm rebar rod that is impaled through the body? I see stories of people surviving impalement all the time, but a shot with a .50 cal to the same area almost always results in instant death. Shouldnt the bullet just go through its target because it travels so fast?

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Anonymous 0 Comments

When a bullet enters the body, particularly military rounds, it creates a cavity (cavitation), basically a giant hole, on the inside.

This pocket is pretty much a vacuum and as such it creates a massive negative pressure because of how fast it forms. What follows is a mini explosion that begins with an implosion of the tissue followed by a massive forced expansion. Think of a balloon squishing till it bursts and the air shooting out in all directions with a pop.

All of that happens INSIDE YOU. That’s not even talking about the fact that it also expands inside you and potentially splits through organs, veins, and whatever else.

A rebar is essentially just going to push tissue out of the way or split it like a knife. It’s not particularly aerodynamic so it doesn’t reach the speeds necessary to cause cavitation. So it pretty much makes a straight hole through you.

Depending on where it hit then, it could kill you or it could not. But it has a drastically lower area/volume that it takes out of the body and thus less of a chance of hitting anything vital.

I’ll look for a video of cavitation… there’s some pretty scary ones with clear ballistic gel that show it. Literally flashes like an explosion.

Here you go: https://youtu.be/fX4ODh1g4eM?t=62s

That video is just with a M855A1 round which is a .556 cartridge. Now look at the size difference between that and a 50bmg: https://qph.cf2.quoracdn.net/main-qimg-3c28291060d552b8c78222580350b19a.webp

Your example of 50bmg is particularly crazy too, because it is made for anti-materiel (not a typo, it means it goes through tanks and armored vehicles). It was made to shoot through fucking tanks. It does not leave much of a person left in its path. It’s fired by machine guns and heavy sniper rifles and is fucking massive.

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