Weird Bullet Behaviour.

[DaavG]

Yeah, things on the Internet are forever, but unfortunately finding the stuff we put on the Internet becomes more and more difficult! It's like when someone at work tells me "it's on the network", and then I tell them "but if no-one can find it, it may as well not exist!"

Anyways... at impact, the bullet deforms (mushrooms) and starts traveling through the target medium. Because the latter is far denser than air, the bullet rotation slows down and the gyroscopic stability decreases. At the same time, (because the center of mass is behind the center of pressure) the thing wants to flip gatoorkop, but this is countered by the gyroscopic stability and the orientation is maintained. At some point the gyroscopic stability reduces to a point where it can no longer maintain the initial orientation, and it flips tail-end forward, which is a stable orientation, because the mushroom creates drag behind the center of mass. If the bullet has enough retained momentum it will therefore punch tail-end first through the opposite skin, but then then get caught by the mushroom, resulting in what you see there.

Is this because the bullet's terminal velocity is at the edge or close to the edge of being stable vs say a complete pass through?

[oafpatroll]

Yeah, things on the Internet are forever, but unfortunately finding the stuff we put on the Internet becomes more and more difficult! It's like when someone at work tells me "it's on the network", and then I tell them "but if no-one can find it, it may as well not exist!"

Anyways... at impact, the bullet deforms (mushrooms) and starts traveling through the target medium. Because the latter is far denser than air, the bullet rotation slows down and the gyroscopic stability decreases. At the same time, (because the center of mass is behind the center of pressure) the thing wants to flip gatoorkop, but this is countered by the gyroscopic stability and the orientation is maintained. At some point the gyroscopic stability reduces to a point where it can no longer maintain the initial orientation, and it flips tail-end forward, which is a stable orientation, because the mushroom creates drag behind the center of mass. If the bullet has enough retained momentum it will therefore punch tail-end first through the opposite skin, but then then get caught by the mushroom, resulting in what you see there.

Thanks for that explanation. I've never found one that I was able to make sense of like that one.

[Geno]

We saw the same thing back in 2013 with G-Force's .338 Lapua mag on a warthog with a 250gr Perergine bullet of sorts.

[Pirate]

Is this because the bullet's terminal velocity is at the edge or close to the edge of being stable vs say a complete pass through?

Perhaps one can argue like that, but the driver is the huge change in geometry and the medium travelled through. What's important is that when you say "at the edge of being stable", we have to understand that that does NOT refer to the stability in air, but rather in the target medium.

[Pirate]

Thanks for that explanation. I've never found one that I was able to make sense of like that one.

Thanks man

[Zuku]

Isn't this a normal case of bullet separation? The outer copper mantel flared open and hit bone, It perhaps flared too much and the inner core still travels forward at momentum when the mantel opened to much and was stop by bone, leaving the mantle behind behind.

[TStone]

Isn't this a normal case of bullet separation? The outer copper mantel flared open and hit bone, It perhaps flared too much and the inner core still travels forward at momentum when the mantel opened to much and was stop by bone, leaving the mantle behind behind.

The Peregrine bullets are monolithic copper alloy bullets, there is no core and no mantle to separate. The bullet in the photo trapped by the skin is the entire bullet.

[Messor]

You guys.

Sent from my SM-A526B using Tapatalk

[Zuku]

Peregrine bullets are monolithic copper alloy bullets,

Sorry, my bad. miss read that part in the OP.