Bullet yaw in this Youtube video

[Nhoro]

Hi all, just watched this video posted by Garand Thumb on YouTube. Pretty amazed at how much the bullet was beginning to yaw and maybe tumble after a fairly short trip through ballistics gel and plastic bones.

 

[Ontario Hunter]

Not surprising. The bullet is obviously a blunt solid and very long. Overly long bullets tend to yaw after impact if they retain shape. What was interesting to me is the bullet trajectory seemed to maintain relatively on track through the target and only seemed to significantly yaw or tumble after exiting. I didn't find the exit wounds to be particularly large. It would have been more interesting if he'd tested a variety of bullets.

 

[BourbonTrail]

@michael458

 

[roklok]

Interesting indeed, these appear to be the Barnes banded flatnose solids. At 10:24 the bullet can be seen yawing well before exit.

 

[Mark A Ouellette]

Bullets in flight do NOT stabilize fully for 10, 20, and sometimes over 100 yards!
The distance depends on velocity, bullet weight and length, barrel twist, and probably other factors.

Chances are those shots at the ballistic dummy were at 10 yards or less and the subject bullets had not fully stabilized. Any bullet with pitch and yaw hitting a more dense medium that the air it was traveling through will probably become more unstable. Remember, bullets are spinning at high RPM.

458 Win twist rate: 1 in 14"
Velocity: 2150 fps
RPM: 110,571

 

[roklok]

Not sure I agree with the bullet stabilization theory. If its not stable as it exits the muzzle, not sure its going to magically stabilize further downrange. Maybe I am wrong on that point. Regardless, the ranges at which the video was showing is consistent with close range DG shots on buff and elephant.

 

[MRBlack]

Hornady had an interesting podcast on bullet stabilization I just finished up. Certainly not as definitive and concise as I would have preferred, but very informative. I believe it was called “Let’s Talk Twist Rate”

 

[Grumpy gumpy]

Ballistics is a complex subject that is often misunderstood, a basic concept is (as explained to me by a ballastician ) is a bullet leaves the barrel unstable, think of all the forces acting against it, and enters the supersonic stage, and at a certain point/distance it settles down as it overcomes the push and spin forces and stabilises (goes to sleep) then at another point/distance it exits the supersonic phase and becomes unstable again. The distances vary depending on exit speed, temperature, etc and bullet weight, it’s coefficient and several other factors, depending on the point in its flight is how it reacts when it meets an obstacle
Simple……….
Gumpy

 

[michael458]

Hi all, just watched this video posted by Garand Thumb on YouTube. Pretty amazed at how much the bullet was beginning to yaw and maybe tumble after a fairly short trip through ballistics gel and plastic bones.

@michael458

Bullets in flight do NOT stabilize fully for 10, 20, and sometimes over 100 yards!
The distance depends on velocity, bullet weight and length, barrel twist, and probably other factors.

Mark is correct on this point, a bullet is not 100% stable as it leaves the muzzle, it takes some distance for it to become fully stable, depending on the factors that Mark listed. With the big bore solids in .458 caliber, a faster twist rate helps with this, but still is not fully stable until some point after exit.

There is absolutely zero science in this little fun video. Just two monkeys having fun is all. There is no mention that I saw of the bullet or bullet design. Obviously this chap is not a hand loader, or serious shooter, and I am sure that is a Factory purchased piece of Ammo. I don't think he even mentions a difference between solid and expanding, his little play time would have been even more entertaining had he chosen an expanding bullet to play with....... You would have still seen some stability issues even then however.

Another part of the equation here is the meplat size of that solid. Meplat size is the driving force behind stability "Once Terminal Penetration begins" in any aqueous material or tissue. Once a Solid starts terminal penetration, it is no longer rear end drive, it becomes fully front end drive, the front "Steers" the bullet, it will either tumble, go off course, or drive completely straight totally dependent upon the size of the meplat. The magic number for Solid Stability during terminal penetration is 65% Meplat of caliber. It the meplat size is less than 65% of the bullets caliber, then it cannot be stable in aqueous material or tissue. Other Factors can assist and increase incrementally the stability of lesser designs, but no matter what, at some point, it will go unstable.

Someone said this was a Barnes Flat Nose Solid....... I don't believe so, it looked more like possibly a Nosler profile or something similar, the meplat looks small, I would guess somewhere around 50%-55% of caliber. A Barnes FN Solid is 65% meplat.

Another factor that falls in favor of Marks comments, all his shots at the BGel is less than 10 feet. I suppose he was afraid he would miss, not being used to Big Bore Shooting........ His Gut Shot, I think the last one, is about 3-4 inches from target.

You guys need to take this for what it is, Two Monkeys playing with guns....... that is about the extent of it.......... I would not take away too much from this play time.

If you like, I can post once again the 8 Factors Of Solid Terminal Penetration...............All of which were tested extensively and proven through real science and 1000s on top of 1000s of rounds tested over many calibers and cartridges, velocities and designs...........

 

[Nhoro]

Regardless of the non- scientific nature of the video, I was surprised by the lack of stability after maybe 6 inches of penetration through soft gelatin and plastic. Nothing like an elephant skull. And I observed the bullet was more stable on entry and noticeably yawning and wobbling on exit. So even if it was not stable yet, it got worse travelling through the dummy.Nothing like the supposed straight line penetration we are supposed to see. I would love to see this done with a variety of bullets.

Close range shots are where I want to see deep penetration, most DG shots are going to be around 50 m or so but life saving shots are probably closer. Especially if an unwounded elephant cow is on your case. National Parks are not going to buy a 50 m self defense shot. More like 10 m.

 

[roklok]

I was definitely surprised. I don't know if the plastic "bones" cause a different reaction than natural bone, but that is not confidence inspiring. As Nhoro said, up close is where straight line penetration is crucial. It did seem to track nice and straight through the gel block however.

 

[PHOENIX PHIL]

Regardless of the non- scientific nature of the video, I was surprised by the lack of stability after maybe 6 inches of penetration through soft gelatin and plastic. Nothing like an elephant skull. And I observed the bullet was more stable on entry and noticeably yawning and wobbling on exit. So even if it was not stable yet, it got worse travelling through the dummy.Nothing like the supposed straight line penetration we are supposed to see. I would love to see this done with a variety of bullets.

Close range shots are where I want to see deep penetration, most DG shots are going to be around 50 m or so but life saving shots are probably closer. Especially if an unwounded elephant cow is on your case. National Parks are not going to buy a 50 m self defense shot. More like 10 m.

Now, whether you realize it or not, you're really entering Michael's territory of experience. I would suggest you poke around his website by first starting here:

Solid Meplat Size Test

Solid Meplat Size Test

www.b-mriflesandcartridges.com

My own little addition to this thread regarding stabilization of the bullet. As was explained to me, when the round is fired, the bullet never engages the lands of the rifle in perfect alignment. It is ever so slightly cocked up, down, left or right. Once this has happened the bullet will continue traveling down the barrel similar to when a football has been thrown without a perfect spiral.

The bullet simply cannot get out of this wobble inside the barrel because the lands have essentially grabbed and hold onto the bullet in this cocked state. The bullet will continue to wobble until it exits the barrel and there isn't anything to oppose the bullet settling in to a nice wobble free twist as it flies down range.