Can any of you relate to us insidents of bullet jackets spinning off and or comma holes in the target? Key holes don't count. Anything other insident which might be related to over stablization ?? The larger the caliber the better.For example I've done it with light .357 pistol bullets in my .358X .404 IMP. Maybe stuff like that. roger

I used to shoot a Swift & had bullets vaporize before hitting the target @ 100yds. These were 45gr Sierras @ 4200fps. If I backed them down to 4050fps they stayed together & printed very tiny groups, shouldn't have sold that rifle.
I shoot a .260ai w/ 27" 1-8 twist & it shoots everything from 85gr Sierras @ 3450fps to 142smk @ 2800fps.

I heard of a guy that "comet tailed" 140 grain bullets in a 30" barreled 6.5-284 once.

I also heard that he liked his whiskey too.

Not to say it can't be done, I've never seen it happen with bullets larger than .224 diameter.

Just trying to see how fast a bullet could be made to go, we caused some 60 grain Winchester OPE's made for a .25-20, I believe, to come apart prior to making it to the paper chronograph screen of an old fashioned Oehler Model 10. This was done by firing them from a friend's .25-284. The velocity of the one shot that did make it through both paper screens registered 4264 FPS.

Yes, I have done this with the 110 gr Speer Varminter loaded to excessive velocities in my 30-06.

This is a large meplat hollow point with much exposed lead. It is designed for use in the 30 Carbine at handgun velocities. It is not difficult to make it self destruct due to rotational forces when loaded with data developed for the Speer 110 gr roundnose bullet, and fired from a barrel with twist rate typical for a 30-06.

After slowing the bullet down to about 30-30 velocities, it made a light recoiling, great fun, plinking round.

i had that happen long ago w/ botha 257 roberts (117 gr spitzers, hornady's probably) and a 270 winchester (130 gr hornady's). these were not in any way hot loads ( i don't try to turn std ctgs into magnums) and was showing up at 25yds. was a very hot, humid day but have not noticed before or since. each bullet hole tho had a spiral of roughly 120-180 degrees spinning out around the bullet hole. i'm assuming was molten lead being thrown off the bullet points by centrifugal force. accuracy was fine, just a strange visual thing.

roger

quote:

Originally posted by Idaho Shooter:
After slowing the bullet down to about 30-30 velocities, it made a light recoiling, great fun, plinking round.

Amen to that. roger

I have had every 140gr nosler BT come apart fired at top velocity in my 7mm 378 wby. I don't know if it was the jackets or theat the bullets were just breaking up.

I intend to shoot VKD bullets for this barrel. I have a fast twist adn will make some 220-270 gr bullets for shooting. These will bring the velocity into the real workd and also pennetrate great. I'll make them like my new design so they expand and should be a great deer, antelope , bear and elk gun. I make the battel just for the hell of it but at sume point will actually settle down and get a load set up for it and take it hunting.

I like to draw blood with all my rifles. Handgins too. Maybe an antelope next fall.

Well thats the only time I've seen bullets fly apart. BTW I don't in anyway feel thi sis a bad report on Nosler. the 7mm 378 wby and super light frangable bullets is a combo that just doesn't go together adn I knew it going in. I was simply curious. The Noslet PT and BT are my faviorate everyday bullet bar none.

John

quote:

Originally posted by willmckee:
i had that happen long ago w/ botha 257 roberts (117 gr spitzers, hornady's probably) and a 270 winchester (130 gr hornady's). these were not in any way hot loads ( i don't try to turn std ctgs into magnums) and was showing up at 25yds. was a very hot, humid day but have not noticed before or since. each bullet hole tho had a spiral of roughly 120-180 degrees spinning out around the bullet hole. i'm assuming was molten lead being thrown off the bullet points by centrifugal force. accuracy was fine, just a strange visual thing. roger

Yes! I'd forgotten (what's new) seeing the gray swirl before and more than once. Thank you for the refresher. Also roger

quote:

I heard of a guy that "comet tailed" 140 grain bullets in a 30" barreled 6.5-284 once.

Vapo, I am not really sure what you mean by "comet-tailing", but on one occasion quite a few years back, I saw something that was very odd. My father was shooting his 7.65 Arg. Mauser, and there was a vapor trail coming off the bullet as it traveled down range. I attribute that to a very humid morning, and the pressure drop at the base of the bullet being just enough to cause condensation. Only time I have ever seen it, and it was pretty neat. Happened with every shot.

Is this just not a case of swirl?

I seem to think you can see this quite easily if you stand directly behind the shooter and try to look down the expected flight path...I recall seeing it quite often when acting as a spotter for guys shooting the old 7.62Nato on the 300m ranges..I think the reason the shooter does not see it more is that he looses the sight picture needed under recoil...

Regards,

Pete

Pete, I think this was different. I was standing off to the side, looking across the shooting lane at an angle. It looked just like the vapor trail off a jet...

I have had this happen in my 6.5 Mach IV shooting Sierra 85 gr. bullets. The bullets never reached the targets. The targets were set at 100 yards. All I noticed was a small puff of smoke downrange. I didn't know this could happen until the guy next to me explained it. I was shooting a small grain bullet too fast through a fast twist barrel. The bullets were spinning themselves to death as he put it.

it is a jacket thickness and construction issue. Varmint pills usually have very thin jackets in any caliber to give you that explosion we all like so much. It also follows the logic that they are NOT a bonded core in any way. Add high speeds from wildcats and fast factory chamberings, and a tight for caliber twist, and you get "core seperation" The bullet tears itself apart like a rocket hitting the atmosphere at full throttle. It simply comes apart and the deterioration gets worse each millisecond as it gyrates more and more out of concentricity (a super-sonic snowball effect).

It happens even with "normal" loads. I had some Hornady SPSX that I thought would be great fur bullets. I loaded some at moderate velocities in the mini-14 and near top end in the .22-250 and they were dust at 25 yards!
The twist rate combined with velocity can be to much, and either one by itself can ruin them. I've not seen it myself but I mentioned it to a guy we knew at the fur sale and he started grinning. He'd been trying Blitz bullets in a .220 Swift. They didn't survive either.

The really fragile ones need to be fired at the recommended velocities.
I also tried the 45gr Speer in the mini pushed with IIRC 26gr of BLC(2), they were pretty fast and worked ok but still damaged the pelts. For the damage and poor accuracy I quit using them.

( I know, accuracy and Mini-14 are rarely used in the same sentence but I guess I got a gem 'cause mine actually does shoot pretty well.) Nate

quote:

Originally posted by Doubless:

quote:

I heard of a guy that "comet tailed" 140 grain bullets in a 30" barreled 6.5-284 once.

Vapo, I am not really sure what you mean by "comet-tailing", .

He was refering to one of my postings. It really is a hole in the target that looks like a COMMA.The case is in the process of coming (spinning)off. roger

the centrifugal forces against the jacket which is more solid than the NON BONDED core make the jacket spin faster than the core, and it comes apart. I would agree your comma shaped holes are the bullet remnants as it is disintigrating,..and if they are repeatable, I would say it was the jacket making most of the holes.

Firstly, centrifugal (center fleeing) force is not a force existing on it's own, it can only exist as a reaction force caused by a centripetal (center seeking) force which is the result of the rotational velocity of the projectile caused by the twist of the grooves in the barrel.

Secondly, rotational velocity together with other minor forces form only about 5% of the total energy behind the projectile.

The larger part of 95% of the energy is used to create linear velocity.

As per a previous post done by Alf:

quote:

I will demonstrate at the hand of an example:

You have a typical rifle projectile with a linear velocity of say 3000 fps and it rotates at 4000 revs per second ( 240, 000 rpm) it will mean the projectile completes 4000 revolutions for every 3000 feet of linear progression,

thus the projectile will only complete roughly 2 revolution per every 16" of linear progression or 400 revolutions per 100 yards.

Given the fact that the projectile or bullet is coming apart, we can clearly see from the above that it is NOT due to centripetal force, but rather as a result of the larger 95% of the force generated through launching the bullet.

Please don't say it is the bullet's "inertia" causing it to come apart!!!

While the 95/5 theory is nice on paper, I find it interesting that the only core seperations I have seen where not only in fast calibers, but were also ALWAYS in a faster twist rate barrels.

This is covered in "rifle accuracy facts" by Harold Vaughn as he describes the core seperation as a result of too high an RPM which is not only related to velocity (liner force) but is also directly related to rotational forces. You can get a varmint bullet in a 220swift in a 1:14 twist at over 4200fps with no problems,..but, run that through a 1:7 twist tube with the same load (same liner forces) and see if that bullet makes it to the target. We blew them up long before 4200fps ever showed up,..and this was in a match tube of far superior internal dimensions and finish.

it is the RPM equation which will reflect an RPM value at which point the jacket and core will seperate. yes linear force is a variable in the equation, but so is twist rate. If one goes down, the other goes up and visa versa. They exist in an inverse relationship to one another. A slower twist tube can be pushed harder, but to acheive the same RPM, the faster twist barrel will require less linear force.

at least that's what I got out of it,..it is a very physics oriented peice of material.

My point is, that every bullet, due to it's construction features, will have a "yield point" where it will seperate. I am sure this is specific to each individual type of bullet. But, there are 2 ways to blow them up

1. push them too fast through a slower twist and arrive at the RPM yield point

2. push them through a faster twist tube at a velocity that acheives the same RPM yield point.

I think

quote:

While the 95/5 theory is nice on paper, I find it interesting that the only core seperations I have seen where not only in fast calibers, but were also ALWAYS in a faster twist rate barrels.

The 95/5 is not only theory it is a FACT! If it was the other way round, then we would have bullets hanging around like honey-suckers, doing high revs and yet staying in the same position or at most moving very slowly ahead.

Therefore a tighter twist barrel not only puts more rotational velocity on the bullet, but much , much more linear velocity stress and hence acceleration/Reaction force on the bullet as well and that again would foremost result in the bullet breaking up faster or more readily than with a slower twist barrel.

This is true because each force has an equal opposing force.

exactly,..the twist rate will affect it given similar charges in similar chambers. They must BOTH be present in the amounts necessary to cause the "yield point" to be reached. Keep slowing the twist and bumping the charge, and you'll get faster and faster,..but, run a heavy twist and much less powder will still result in a jacket shedding. I have run bullets extremely fast in light twists,..with all bullets making round holes in the target (although poor groups). THEN, when we bumped the twist rate considerably,...POOF,..the bullet was shrapnel. I find in the offerings we have today, that the velocity for each cartridge (within sane limits) is stable across the board for all pills (within reason) but when a match tube with a far faster twist is applied,..even some of the fatory ammo in the swift we experimented with went POOF. Only change was the twist rate. Eventually the 80gr and up pills were the only ones which did not go POOF. Anything under 80gr's was dust in the wind. Now,..when wayyyyy downloaded, they stayed together,..but this was in reality no longer a swift and more akin to the 223 or a mild 22-250 load.

I see that the numbers of 95/5 can often be very close to the real results on paper when mathmatics is applied,..but I don't go that far. There comes a point in a fast twist tube, that you will see destabilization starting before a light construction pill blows up, it is then that you have to back powders down to get it stabil, as you can't change the twist rate without changing the barrel. I have yet to see a blow-up in slow twists (maybe just a coincidence, I don't have enough blow-ups in my portfolio to consider it a good data set) BUT, every blow-up I have witnessed has been in a fast twist. So if twist rate transfers to linear energy as well, that linear increase is partnered with the twist,..symbiotic if you will. Hence my standpoint that twist increases will bring about the seperation given you are working with the same chamber, same cases, same bullets, and same powder for both experiment barrels.

Back in the early late 1960s I once fired some 30-06 factory Rem Bronze Points (180 gr) from my uncle's pre-64 Model 70 Win trying to sight it in. Had a standard target stapled to a cardboard box at 100 yards.

After firing 3 rounds I went up to the target and found the empty jacket of one bullet barely sticking in the face of the target with the entire lead core missing. The other two jackets were laying on the ground in front of the target.

Needless to say, my uncle took the "evidence" back to the store that sold him the ammo and got it replaced with some CoreLocks.

It was not the rifle. After that, I took up reloading and fired many rounds through that same rifle with no problem.

Barstooler

after further investigating Vaughn's experiments this evening, I also find that he startes by determining the Brinnel (sp) hardness of the cores of each bullet he is testing. That BHN rating is then apllied to an equation he uses which incorporates chamber pressure of the load, and the core temperature at moment of firing to arive at a measurement of the "spin-up torque" in ft/lbs at which point that BHN hardness core will seperate. He was right on all tests that the bullet core and jacket were failing or showed initial signs of failure buy biulding an instrument which measures the RPM's of the bullet as it passed through it. He used a barnes X bullet of solid construction with no lead core to establish the baseline, and then tested each bullet through that machine. If the RPM was slower than the X bullet, the core was seperating due to the "spin-up torque" pressure being too much. The same rifle and twist was used throughout each caliber tested, so twist rate was held constant. he also incorporates the rearward pressure of the ignition and how it acts upon the core of the bullet by pressuring it rearward inside the jacket which with an increased twist rate would stand to reason will become higher thus imparting a greater rearward force on the core material as the faster twist makes the bullet entry a bit harder.

What he did was worked into the RPM figure by using a totaly different base-line of spin-up torque. His calcualtion uses INTERNAL balistics to prove what EXTERNAL balistics proves through another approach. external will prove when an RPM is reached in a certain bullet, it will have a core seperation,..internal method proves that a certain twist rate, at a certain chamber pressure, with a certain BHN value of the core, that it will exceed the spin-up torque value and if the calculation is run ahead of time, the round will never have to be fired. Running at the limit of seperation will never be productive, so the equation will give the chamber pressure you need to stay under with any pill as long as a BHN value is determined relative to it's core material. AND, as this value varies from bullet to bullet, so does the RPM (result of velocity and twist) at which each individual bullet can run before the spin-up torque overpowers the density of the core and seperation occurs.

JustC:

Looks as if you are just playing around with rifles and loads.

If your objective is to shoot something, why would you endeavour to blow up the bullets before it hits the target?

Suggest you go to monolithic bullets if you require more speed - that will solve your seperation problems permanently.
Let's have your results once you've tried these.

Don't play around with rifles - they are dangerous pieces of equipment!

SpringTrap,..Most all of the rifles I have are in posession of at least 2 match worthy loads, so experimenting is a luxery I enjoy. I like to prove and/or disprove a theory or quandry that I have come up, so I go and do my best to definitively find an answer. I am a student of the science and not simply just a handloader for hunting accuracy. I like to experiment,..that's the foundation of the handloading hobby.

Monolithic bullets do not interest me, as my Match tubes are really not worth running mono's down them when they won't produce the MOA I am looking for.

as for trying to blow things up,..when you work with wildcats enough, you run into these situations. The swift we blew up bullets with was in a 1:8 twist barrel, which is going to be extremely hard on light jacketed pills at the velocities it will create in a 28" barrel,..so we knew some pills were just going to not like it. It wasn't until the pills were becoming particulate quite regularly that the magnitude of the whole RPM factor set in as much as it did. The expectations were NOT that extreme,..but once again the real world trumps theory.