Bullet failures

[WildRose]

To add.

This was a problem for a lot of people shooting really fast rounds through gain twist barrels. The angle on the grooves and lands is constantly getting tighter and that puts extreme stress on the jacket so with thin jacketed bullets it's a real problem.

 

[WYOHTF]

Well, slow spin doesnt' cause bullet failures. Fast twists and especially at high velocity can however rip a thin jacketed bullet to pieces.

Mono's are longer than comparable cup/core bullets by 10% or more. Thus, you need to go at least one rev faster than for a cup/core bullet of comparable wt

Agreed
Think we said the same thing
Except I didn't bring up mono bullets specifically.

 

[codyadams]

Well, slow spin doesnt' cause bullet failures. Fast twists and especially at high velocity can however rip a thin jacketed bullet to pieces.

Mono's are longer than comparable cup/core bullets by 10% or more. Thus, you need to go at least one rev faster than for a cup/core bullet of comparable wt

Slow spin can cause a bullet to fail to perform, if a bullet isn't properly stabilized then upon impact, instead of performing as intended it can yaw and begin to tumble. This is more common with monos, but certainly does happen with some common twists and heavy for caliber long c&c bullets. An example is the Berger 170 grain .277, almost all common .277 bores are 10 twist. It is possible to have them shoot acceptably accurate in a 10 twist if your lucky, but it will not be stabilized and have a high likelihood of tumbling upon impact.

Again, this comes back to human failure to use the bullet properly as is the common narrative, however a bullet shot from too slow of a twist can certainly fail to perform.

 

[Canhunter35]

That depends on the bullet, what it hit, at what angle and how it was designed.

Lot's of variables there. If I put a 375 Solid into the shoulders of Wildebeest, or Buffalo up close and it doesn't exit, I know something is wrong. It didn't track straight through as designed.

If it turns 90 degrees instead of tracking straight through, I know the bullet failed to perform as designed even though it was used exactly as intended.

Now if I put that same bullet through an Oryx and that Oryx runs a couple of miles before cratering, I know it also performed exactly as intended even though the Oryx did not die quickly.

Conversely if I shoot a Hornady Amax out of my 300Rum and it blows up on impact horribly wounding the animal, that's my fault for using a target bullet in a hunting application.

When I see a bonded bullet flatten out the size of a quarter or half dollar on impact with bone and turn 90degrees or more I know the bullet failed to perform as designed.

If I hit a deer with a Nosler Partition in the ribs and close range I know that bullet will pencil straight through and I'm probably going to have to anchor it with another shot or do some tracking.

If that bullet however blows up shallow when it hits the humerus or scapula, I know it failed to perform as intended.

No shooter, rifle, caliber, cartridge, or bullet is perfect and none of them are designed to work right in every imaginable circumstance.

We improve our odds greatly by using the bullet as it's designed and pick our POI accordingly and hit it, but every once in a rare while, they just don't do what they are supposed to do.

Still confused why Terri Anne quoted, yes, in my original post I said if a bullet penetrates enough to wreck internal organs and animal doesn't die instantly because they can be stubborn about it, it's not a bullet failure. As long as a bullet is capable of penetrating over halfway, the placement is up to me to make it happen

 

[WYOHTF]

Slow spin can cause a bullet to fail to perform, if a bullet isn't properly stabilized then upon impact, instead of performing as intended it can yaw and begin to tumble. This is more common with monos, but certainly does happen with some common twists and heavy for caliber long c&c bullets. An example is the Berger 170 grain .277, almost all common .277 bores are 10 twist. It is possible to have them shoot acceptably accurate in a 10 twist if your lucky, but it will not be stabilized and have a high likelihood of tumbling upon impact.

Again, this comes back to human failure to use the bullet properly as is the common narrative, however a bullet shot from too slow of a twist can certainly fail to perform.

Thanks,
I hadn't thought of that and probably should have, not to long ago I read about a 50 cal bullet test somewhere. They shot he bullets into sand at distance and recovered the bullets and sand marks in the bullets told them in what fashion the bullets impacted the sand. It was all about twist.
I think it was something Kirby Allen shared, not sure though

 

[BigDon]

Well Wild Rose I will bow to your multitude of animals killed but examining wound tracks in the field is hap hazard at most. Not to denigrate your experiences, but in less than a full necropsy laboratory I would find it hard to do any kind of a determination relating to a supposed bullet failure out in the woods or fields instead of a lab. Our thoughts do not necessarily revert to facts until proven scientifically.

If you're doing a field necropsy, I would maintain that the bullet did not 'Fail'. You may not like the on-animal results - but the bullet did not fail.

 

[Pdvdh]

If you're doing a field necropsy, I would maintain that the bullet did not 'Fail'. You may not like the on-animal results - but the bullet did not fail.

Not even if the animal had to be shot a 2nd time, 25 minutes later, after being broadside double lung shot from 12yds with the first bullet?

We have much different definitions of bullet failure. An expanding bullet manufactured and promoted as a hunting bullet that fails to expand on any solid body hit at 2,700fps impact velocity, is a classic "bullet failure".

Some must have never experienced a bullet failing to expand, or a bullet shrapnel on impact to the point of failing to penetrate sufficiently to cause anything other than a surface wound.

A observant person doesn't have to be a veterinarian, surgeon, or rocket scientist, to be able to identify some of the obvious bullet failures.

 

[Rich Coyle]

Animals are a lot like Humans. Shot where they have no reason to still be standing, yet they do and may even fight back although they are dead and don't know it. That was one of the major requirements for the 1911, knock them down or throw them back which it did well until you got the humanitarians involved. Across the pond had occasion to check out this theory. It did work just as advertised. Same goes for rifles and deer. I need say no more.

No. You need to learn from others.

 

[WildRose]

Slow spin can cause a bullet to fail to perform, if a bullet isn't properly stabilized then upon impact, instead of performing as intended it can yaw and begin to tumble. This is more common with monos, but certainly does happen with some common twists and heavy for caliber long c&c bullets. An example is the Berger 170 grain .277, almost all common .277 bores are 10 twist. It is possible to have them shoot acceptably accurate in a 10 twist if your lucky, but it will not be stabilized and have a high likelihood of tumbling upon impact.

Again, this comes back to human failure to use the bullet properly as is the common narrative, however a bullet shot from too slow of a twist can certainly fail to perform.

True, slow spins cause instability, keyholing etc they just don't tear bullets apart. Fast spins, especially in gain twist barrels can shred thin jacketed bullets.

Overspin I've never seen to be a problem but some of the bench shooters used to sear that if your twist was too fast bullets would not "tip over" in flight and give inconsistent results. Personally I've never seen it.

 

[WildRose]

Still confused why Terri Anne quoted, yes, in my original post I said if a bullet penetrates enough to wreck internal organs and animal doesn't die instantly because they can be stubborn about it, it's not a bullet failure. As long as a bullet is capable of penetrating over halfway, the placement is up to me to make it happen

No argument from me. I usually quote the posts I respond to so we don't' get lost.

 

[WildRose]

If you're doing a field necropsy, I would maintain that the bullet did not 'Fail'. You may not like the on-animal results - but the bullet did not fail.

If it didn't perform as designed and intended, it failed. That doesn't necessarily mean the animal isn't dead.

When an SGK made a perfect center hit in the chest of a large deer and deflected to open the rib cage up like someone took a hatchet to it, that bullet failed to perform as designed.

If a HP conventional bullet fails to expand passing through the heart and lungs, and pencils out the other side, it failed to perform as designed.

You may still recover the animal, but the bullets still failed.

 

[RockyMtnMT]

you see a lot of complaints about the old Barnes X. if there is one thing we learned from Hammer bullets is that monos need to be spun fast and wondering if it is a stability issue more than a bullet issue.
anybody here ever run the Barnes X in fast twist barrels?
after reading through this tread and thinking i am starting to wonder if we are having stability issues instead of just bullet issues especially with some if the older chamberings that normally come with slow twist barrels

This I believe is dead on. I have posted many times about our experience impact testing bullets and learning the relationship of stability and terminal performance. Just because a bullet is ballistically stable and shoots lights out does not mean it has enough rotational vel to perform properly on impact. There is no calculator to determine terminal stability. All I can tell us what we have concluded. I'll add that the longer a bullet is for caliber the more critical this gets. Short bullets have much less terminal performance issues. We determine min required twist for hunting with the Miller stability formula but never enter in altitude. A 1.5 sg calculated at sea level standard atmosphere is considered minimum for proper terminal performance. I personally want to see a stability factor close to 2.0 sg calculated at sea level for my personal rifles. I think it is very likely that experience of bullets changing direction after impact or not opening on impact is a result of running to low of stability. rpm's is what keeps the bullet point on after impact. If the bullet does not stay point on long enough for the bullet to fully deform it will likely change direction, tumble, or pencil.

My next chore is to add a preferred twist rate to all of our bullets along with our minimum twist that is currently listed.

When it comes to bullets that are not able to open if the impact velocity is too high. I am not sure how this could be possible. The only way to prove this theory would be to shoot this bullet into gel at high velocity and see if it will open after x inches of penetration once it has slowed enough to open. Then shoot the same bullet at lower impact velocity to see if it will open with less penetration. My experience impacting bullets is they do not have speed sensors in them. Nor do they have depth sensors telling them when it is time to open or when it is time to stop penetrating once they have reached the far side of an animal. What I do know is that a bullet that will open at xxxx fps will open more rapidly the faster the impact velocity gets. It is certainly possible to impact a bullet faster than it can handle, causing it to lose all integrity and fail to retain enough mass to continue on its directional path. I remember hearing the stories when I was young about how magnum rifles would fail to open bullets at short range and they would just zip through so fast that the bullet couldn't react quickly enough to cause damage. If this was true the bullet would expand after exiting the animal. Another campfire legend passed down through the generations. If someone can show me a test of lower velocity expanding a bullet better than high vel I will eat that crow without seasoning!

 

[RockyMtnMT]

Once a bullet impacts something, its stability is immediately compromised though, especially when it begins deforming and/or coming apart.

This is very interesting too. Something else we have learned that I would have bet against. We have figured out that a lighter bullet that sheds the nose will out penetrate a heavier bullet that sheds no weight. This goes against the math that says the heavier projectile will have more momentum which would result in traveling farther through the animal or test media. This also comes down to stability. The heavier projectile that is carrying more momentum is also longer. Because it is longer it needs more rpm's to keep it point on. As it loses rpm's it begins to turn sideways. Now it greatly increased the surface area that the media is reacting to and causes the bullet to stop faster resulting in less penetration. The bullet that sheds it's nose winds up with a shorter retained shank that will maintain stability longer while paying through the media resulting in greater distance of penetration. If too much mass is lost on impact then this would result in less penetration. So there is a line where this is no longer true.

 

[RockyMtnMT]

Well Wild Rose I will bow to your multitude of animals killed but examining wound tracks in the field is hap hazard at most. Not to denigrate your experiences, but in less than a full necropsy laboratory I would find it hard to do any kind of a determination relating to a supposed bullet failure out in the woods or fields instead of a lab. Our thoughts do not necessarily revert to facts until proven scientifically.

How do you evaluate bullet success or failure?