quote:

Originally posted by ALF:
HC: What is so confusing about what I said ?

I'll dummy it down !...So if you wish me to illuminate why I say so I can expand. ...

Hey alf, Yes indeed, expand away. Surely there is more to it than that.

Sure appreciate you "dummying it down" for those of us who don't know nothing about them Ballistics.

I am aware of a handgun test where they were shooting into either modeling clay or plumbers putty.

They used 2 different 9mm's.

One had a twist of 1 in 16, the other 1 in 10.

The faster twist had larger wound channel.

H/

From an outsiders point of view it appears as though Hot Cire was only asking for clarification.....not at all arguing.....did I miss something?

quote:

Originally posted by ALF:
HC, as I have asked you on more than one occasion do prove me wrong please on what I have stated .

Why alf, I'm shocked that you would think I have an ulterior motive.

quote:

You love to criticize and ridicule but offer no counter argument to disprove what I have stated to be in error, so once again without further ado I bow before your superior knowledge and intellect on all matters shooting, so please feel free to correct me on anything I have posted.

Tell you what I'll do, I'll give you my word that I will not post to this thread again. I simply want to try and understand what your vast, limitless guru wisdom concerning Ballistics is trying to tell me. So.... expannnnnnnnnnd away with your dummied down version. I only hope you are able to dummy it down enough that I'll be able to understand.

I won't criticize or comment at all.

I've been killing deer/elk/caribou, etc. for many years with 10 and 12" twist '06s and .308Ws. I've shot them from 20 to 600 yards. I never could tell a difference in "killing" or "meat damage" between either twist.

One thing I can say is that i measure BCs via a M43 Oehler with screens at the muzzle and screens down range at 100 yards. Comparing BC given the same bullet at the same relative velocity in 10, 12 and 14" twist barrels it is readily apparent that the 12' twist consistently gives a higher BC out of the 12" twist with bullets of 150 to 180 gr (BT, FB and match). The 10" twist gives higher BCs with 190 to 220 gr bullets and the 14" twist gives higher BCs with 110 to 147 gr bullets. Some of the BCs for some bullets on each end of each spectrum overlap to some degree.

Since accuracy and stability is excellent with the 12" twist up through 220 gr that is my my choice for a .308W or 30-06 if only jacketed bullets are used. If I'm going to shoot a lot of cast bullets, particularly hunting with them, then i would go with a 14" twist and be happy with FB's 180 gr bullets as a max. However, the 12" twist still makes the best overall twist for the '06.

Larry Gibson

I don't see where twist rate will or can effect BC as long as you have enough twist to properly stabilize the bullet. More twist is not going to hurt

Here is what Brain Litz (Ballistician for Berger Bullets) has to say on the subject. Brain tests for BC with a 600 yard spacing

quote:

Bryan Litz
Sergeant

Registered: 24-08-2008
Posts: 95
Loc: Ohio Ratbert,
Thanks for your comments. Fortunately we're all on the same page at Berger as far as doing what it takes to enhance the shooting experience, regardless of brand.

DB,
Actually the window of proper stability is quite large. On the low end, you have to use at least the minimum recommended twist. On the high end, well, most of the adverse affects cited for over stability are myths. The most adverse effect of very high stability levels is extra spin drift. Other than that, elevation is not affected and BC is not affected.
I think most of the myths about over stability stem from imperfect understanding of the sights including: imperfect zero, click adjustments not being true, canted reticle, etc.
I occasionally see cases of extremely high (and low) BC's being reported by those conducting tests. You'll find that in most of those cases, the non-physical results are caused by oversights in the test.
It's a comfort to know that most of the smoke and mirrors surrounding BC is just that; smoke and mirrors. At the end of the day, actual BC's are very well behaved and constant from all rifles across a large range of stability levels. If two bullets have the same shape and one is heavier, the heavier one has a higher BC. If two bullets are the same weight, and one is more streamlined, the more streamlined one has a higher BC. This is common sense but many 'advertised' numbers contradict these basic trends and it causes unnecessary confusion.

Take care and good shooting,
-Bryan
_________________________
Ballistician
Berger Bullets

quote:

So.... expannnnnnnnnnd away with your dummied down version. I only hope you are able to dummy it down enough that I'll be able to understand.

Hot Core,

I will take it then that you still trail behind in Alf's second explanation (dummy version). You are wanting him to dummy it down further. Which part of the explanation is not clear or is it the whole flippen concept that you cannot rap your head around? If it is none of the above, what could it be then .... ?

ALF,

We had a similar discussion some time back here on AR about CZ fitting a 1-in 9" twist to the 9,3x 62mm, instead of the traditional well proven 1-in 14". This is not a marginal change in spec, but a dratic/extreme one. At the time I questioned the sensibility of this move in terms of the benefits it would bring. Let us use a heavy bullet, a WDL 320 gr SN bullet at 2,100 fps (that is what I am getting in my rifle with my load):

a) 1-in 14" yields a spin of 1,8000 revs/sec
b) 1-in 9" yields a spin of 2,800 revs/sec

In terms of calculated SF, the values are as follows for the above:

a) SF = 2.11 (A required twist rate of 16.6" is needed for SF = 1.5)
b) SF = 5.11 (A required twist rate of 16.6" is needed for SF = 1.5)

Surely this shows that the additional twist is superfluous?
What would the position be of compliance with CIP?
What is your opinion on this?

Warrior

Gerard posted 21 March

quote:

When a bullet transitions from flight to tissue, especially if it arrives at a steep angle of incidence, it needs a stability factor of at least 1.3 (1.4 or higher is preferable) to make the transition without getting sideways. Once the transition is made and it has been done without excessive yaw (during transition), stability factor becomes a non issue. Other parameters determine how deep and in what manner the bullet will penetrate. A bullet that swings the tail on impact has little chance after that.

Brazos Jack

quote:

Can't buy Gerard's explanation.

This is because you guys keep missing what I am saying about stability factor at impact and the transition from flight to tissue. Example:

quote:

However, no bullet will be remain gyroscopically stable in a medium substantially denser than air, like tissue.

This is precisely what I have said many times: "Once the transition is made and it has been done without excessive yaw (during transition), stability factor becomes a non issue."

With the rest of your post you agree with me that tighter twists give better terminal ballistics results with a wider range of bullets and under a wider variety of conditions, so what is there that you do not buy?


Alf,

quote:

If I take your 180 gr GSHV and fire it from 3 barrels, 1:10 , 1:12, and 1:14; all under same launching conditions and all impacting at the same impact velocity at say 300 m that the 1:10 barrel is going to give somehow "less or more meat damage" whetever that means than say the 1:12 or 1:14 barrel?

We do not make a 180gr HV as it cannot perform terminally, to our standards, in a 1:10" or slower barrel. But I follow your question and the answer is: Yes, the slower twist rate is more likely to result in a bullet that tumbles or deforms asymmetrically or turns in the animal when monometal soft bullets are used. Monos that tumble cause more meat damage and are unpredictable in the way the perform terminally.

quote:

And that different "rules" apply in the Gyro theorem between a Mono bullet vs a cup and core bullet?

Not while they are both in flight in air or while in "flight" in tissue, but during transition yes, because the behaviour of monometal bullets differ from lead core bullets in that phase.

quote:

But his still does not answer my question, how exactly if the bullet is deemed "stable" at impact does twist rate influence wounding capacity????

You are over complicating matters and not hearing what I am saying: Stability factor plays a role during the transition from air to tissue. Not during flight in air or during penetration in tissue - during the transition from air to tissue - transition from air to tissue - transition.

quote:

I did a search of articles that deal with impact condition of the bullet specifically in terms of the reltationship between yaw at time of impact.......

Yaw angle on impact and the minute differences for the same bullet from different twist rates is a non-event when we discuss flat fire (say to 500m). The significant fact is the stability factor. Question: Which bullet resists the impact generated overturning moment better? One with a stability factor of 1.1 or one with a stability factor of 1.5?

quote:

Question: Will shooting a 30 cal bullet of say 168gr fired from a 1:10, 1:12 and 1: 14 twist rate barrels cause significantly different wounds at normal hunting ranges, say 200 and 300 m all else equal ? The short answer is: No !

If it is a lead core bullet you could be correct - If it is a monometal bullet the short answer is in fact "Yes".

quote:

All else equal, all that is different at time of impact when similar bullets are fired from the 3 different twist rate barrels would be angular velocity

That is where the significance lies. The shorter bullet would be going faster and would have a higher stability factor than the longer bullet. The angle of attack has almost nothing to do with the transition from air to tissue at usual hunting distances.

quote:

So with this established; how does impact condition effect bullet performance in target?

The bullet with the higher s/f better resists the overturning moment that is generated between the center of pressure and the center of gravity. The bullet axis, which is in effect the axis around which the gyroscope spins, is less likely to assume a different plane and the base of the bullet is less likely to try and overtake the nose. It deforms more symmetrically and has a better chance at linear penetration.

quote:

In order to establish this relationship one will have to negate any variables that would confound the "test" or assumption, such as, fragmentation or bullet deformation.... so a non fragmenting, non deforming bullet can be chosen to do the test.

Such a test, and the ones you quote, are therefore invalid in a discussion of expanding, hunting bullets.

quote:

or the longer and skinnier the bullet, the quicker the bullet tumbles

Longer skinnier bullets have lower s/f values. You understand the concept. Why are we discussing this?

The posts below all go to stable flight. Stable flight is easy and can be had with a wide variety of twists, bullet weights and stability factors. When shooting paper and steel from close distances and out to 1000yds, all below are true. This is not what a typical CZ550 in 30-06 will be used for.

quote:

LEt me point out that most 308/7.62NATO target rifles which are shot out to 800 & 1000yards are typically built with 1:12" barrels and are intended to shoot 180gr and 190gr match bullets.

quote:

I have a very accurate Rem 700 Police in .308 Win. I was told that the 1-12" twist was meant for the 168 MK bullet. As a matter of fact, 168-175 match bullets seem to be the standard among sniper circles.

quote:

I spent years shooting the national match course out to 600 yards with M70 Win and M1A in .308 with 1 in 12 twist. They shot great with bullets as heavy as 190 gr Sierra Match

quote:

I spent years shooting the national match course out to 600 yards with M70 Win and M1A in .308 with 1 in 12 twist. They shot great with bullets as heavy as 190 gr Sierra Match

quote:

I will try 150 gr on up to 220 just to see if any keyhole,

quote:

I have fired 220 grain RN bullets in my 1/12" twist .308 pre-64 M70 at 2200 FPS with good accuracy results.

The second post in this thread, from DMB, puts it in a nutshell.

As Alf pointed out, the 'SF value' is not the only factor in assessing stability; there is also the question of 'tractability' that plays a role when the bullet hits the target as to how the bullet will behave. Tractability is the dynamic of the nose of the bullet following the flight path.

Bullets can be over-stabilized, as the SF value goes up and up .... from say 1.0 (just stable in air) to let us assume 5.0. So a higher SF is not necessarily better. What happens when a bullet is over-spun or over-stabilized - there is more drift for one, and the bullet flies with its nose up throughout the flight path to the target. This is actually a more serious problem with distant targets due to the trajectory angle, than at shorter ranges out to 200 yards, where the trajectory is flatter (the bullet will cover a shallow arc that is almost flat). When this happens we see a few things:

a) more air resistance as the bullet does not fly point-on,
b) which negates a good BC and bullet drop is enhanced, and
c) keyholing on the target at longer ranges, and
d) the angle of attack is increased on contact with the target

So my contention is that an adequately stabilized bullet (SF = 1.3 to 1.5) is more preferable than a totally over-stabilized bullet that flies with its nose up. Target shooters therefore opt for twist rates that would 'just stabilize' a particular bullet (or just a bit more for colder conditions/increased air density), as the 'just stable' bullet flies with its tip forward all the way. They (target shooters) are quite adamant and particular about this - e.g. the 155 gr Palma bullet call for a very narrow range in twist rates to achieve its best accuracy and rentention of velocity to remain above 1,116 fps (Mach 1 at sea level) and that means that the bullet must fly point-on, so it works hand in hand with its designed BC (sleek design) and not against it.

So how ideal could it be that we engineer a high SF bullet of say 5.0 or even more, traveling with its nose up, at hunting ranges from 200 to 500 yds, with a more pronounced angle of attack? Needless to say the tractability condition gets progressively worse beyond 500 yards. Once a bullet has been sufficiently stabilized, there is no point in spinning it faster.

Warrior

In an attempt to make it clearer for Hot Core:

http://www.fulton-armory.com/fly/tractf.htm

"The tractability factor f characterizes the ability of the projectile's longitudinal axis to follow the bending trajectory. The quantity f can simply be defined as the inverse of the yaw of repose. It can be shown that the tractability factor f is proportional to the inverse of the gyroscopic stability factor."

There comes a point of diminishing returns with gyroscopic stability condition (SF Values), in fact in more extreme cases too much of a good thing can be a bad thing (it works against tractability). Why design something away from the ideal position? In practice, you want the SF value to be a little greater than 1.0 to allow a margin for error such as imperfect calculations, imperfect barrel twist, non-standard atmospheric conditions, etc).


The notion that the value of a high SF-number lies in the "fact" that it helps in transition from air to flesh is simply a myth. We know that flesh is about 1,000 denser than air and that the SF statitic just relates to AIR stability and not to FLESH. So even a bullet SF value of 5.0 (1.0 being 'just stable' in air) that is way over-stabilized, is way off the mark for flesh, which is a 1,000 times denser, to have any material/significant effect.

Warrior

WARNING!! HERE STARTS A THAT EXTENDS TO THE END OF THE THREAD

The two posts above from Warrior/Truvelloshooter/Chris Bek apply to shooting at distances way beyond normal hunting range with a standard 30-06 rifle.

The discussion here is about hunting and shooting inside 500 but, there are two differing cocepts here and we know he has trouble considering more than one at a time.

Differences in axial angle of attack caused by yaw angles, tractability, slow and fast precession cycles and so forth, are so small that they may be ignored at distances inside 500 - unless you are lobbing rocks. He commented on this a number of posts back but probably forgot. Its that 'more than one concept at a time' thing again that he always has trouble with.

His posts spotlight his confusion around the subject very well and renders his "contention" and opinion worthy only of file thirteen.

Giving the Fulton Armory link, as though he understands what is being discussed in the link, is a bit of a laugh. Clue: Chris, see the capital H in the circle in the formula. What do you think it means?

His posts do raise two questions about which I am curious:
1.

quote:

So how ideal could it be that we engineer a high SF bullet of say 5.0 or even more, traveling with its nose up, at hunting ranges from 200 to 500 yds,

Now I wonder which manufacturer has such a bullet? Probably he is just confused about which thumb he is sucking. Having two thumbs at once must be the problem.

2.

quote:

The notion that the value of a high SF-number lies in the "fact" that it helps in transition from air to flesh is simply a myth.

Other than his opinion (which we have seen is worthless and confused), it would be interesting to see what else he would offer as proof of this "myth"? Some research perhaps, or some comparative testing? Maybe another's noted opinion based on a smidgen of research or testing? Of course we have "air" and "tissue" - two concepts again. He has no chance of getting his head around this one.

He is such a buffoon. An entertaining buffoon, but a buffoon none the less.

The notion that the value of a high SF-number lies in the "fact" that it helps in transition from air to flesh is simply a myth. Yes, a false believe !!! This claim is made by none other than Gerard Schultz, and he can observe this occurance with the naked eye (sic) in the hunting fields at practical hunting ranges of South Africa. That is what he is telling us, in the face off ....

We know that flesh is about 1,000 denser than air and that the SF statitic just relates to AIR stability and not to FLESH. So even a bullet SF value of 5.0 (1.0 being 'just stable' in air) that is way over-stabilized, is way off the mark for flesh, which is a 1,000 times denser, to have any material/significant effect.

There comes a point of diminishing returns with gyroscopic stability condition (SF Values), in fact in more extreme cases too much of a good thing can be a bad thing (it works against tractability). Why design something away from the ideal position?

Incessant efforts to ridicule one's opponent is not the way a confidant person tackles an issue. This is not the way to persuade. Stay with facts and logic, they are much more powerful, rather than heavy reliance on caricature to try to sustain one's position.

Warrior

Interesting. I see three questions asked that remain unanswered.

quote:

Question: Which bullet resists the impact generated overturning moment better? One with a stability factor of 1.1 or one with a stability factor of 1.5?

quote:

1. quote:
So how ideal could it be that we engineer a high SF bullet of say 5.0 or even more, traveling with its nose up, at hunting ranges from 200 to 500 yds,

Now I wonder which manufacturer has such a bullet?

2. quote:
The notion that the value of a high SF-number lies in the "fact" that it helps in transition from air to flesh is simply a myth.

It would be interesting to see what else he would offer as proof of this "myth"? Some research perhaps, or some comparative testing? Maybe another's noted opinion based on a smidgen of research or testing?

Do the learned gentlemen at whom these questions are directed have answers or not? I see Gerard answering questions but when he poses questions in return.......... there is silence.

quote:

Do the learned gentlemen at whom these questions are directed have answers or not? I see Gerard answering questions but when he poses questions in return.......... there is silence.

I see it somewhat like a city full of Democrats.....if they are the answer, then someone sure as hell is asking the wrong question!!!

quote:

If you shoot copper monometal bullets, you are limited to no heavier than 140gr if it is a boat tail bullet. Heavier monos will shoot accurately but terminal failures will increase, as the length increases over 140gr. Gerard Schultz

Let us look as some data:

.308, 140, Barnes 'X' BT 30810 has a length of 29.08 mm
.308, 150, Barnes 'X' BT 30817 has a length of 30.61 mm
.308, 165, Barnes 'X' BT 30827 has a lengtgh of 33.02 mm
.308, 180, Barnes 'X' S 30835 has a length of 34.29 mm

Now most rifles in 30.06 Spr and 300 Win Mags are fitted with a barrel with a twist rate of 1 in 10". Most hunters that I know of use all the time the 180 gr Barnes-X bullet (the longest one in the list) successfully.

Like wise, the 150 gr Barnes-X bullet is quite commonly used in the 308 Win with a twist rate of 1 in 12". This notion that terminal failures will increase when a copper mono-metal bullet goes heavier than a 140 grainer is pure horse shit. (going from a length of 29.08 mm to 30.61 mm will cause more terminal failures)

I am curious to learn the cut-off SF values for the above conditions as specified by Gerard. Once we have his specification for crossing the rubicon, we can start the debate from there.

Gerard should be lecturing this to the Barnes-X company, and I would like to be a fly on the wall.

Warrior

quote:

Gerard should be lecturing this to the Barnes-X company, and I would like to be a fly on the wall.

I see on the Barnes website

quote:

What rate of twist will stabilize Triple-Shock X Bullets?

TSX bullets are designed for and tested in standard-twist barrels. If you’re using a slower twist, we recommend choosing a shorter (lighter) bullet for your rifle. (See General Reloading section for a list of our test barrel twists.)

When I use TSX Bullets, should I choose a lighter bullet than I’d normally use?

Because Triple-Shock X Bullets retain nearly 100 percent of their original weight and penetrate so deeply, many shooters select a lighter-weight X-Bullet or TSX in place of a heavier conventional bullet. The lighter TSX Bullet delivers higher velocities and a flatter trajectory, and outperforms heavier bullets of conventional design. It also produces less recoil.

Is that not what Gerard has been saying for a long time? I also see in the Barnes load data that they use a 10 inch twist for all the 30-06 loads except for the 165 gr banded solid. I see a 12 inch twist is listed for that.

I also see that many bullet manufacturers have followed the GS Custom lead with flat nose solids and pressure reducing attempts on their solid shanks. Maybe they have been listening to Gerard. Maybe they were the flies on the wall?

However learned gentleman: I still see no answers to the three questions. But you have the temerity to pose further questions. You have a strange idea of how discussion and debate is supposed to work.

quote:

However learned gentleman: I still see no answers to the three questions. But you have the temerity to pose further questions. You have a strange idea of how discussion and debate is supposed to work.

VVarrior,

It has been pointed out with your similar web-name that you must be a premature reincarnation of Gerard himself.

You do not seem capable of following the argument. It is about SF values and their specific role that is claimed by Gerard and the cut-off values on SF as a maximum bullet weight of 140 grians for mono-metals. And then this amazing observation capability of Gerard as to the small differences in angle of attack at practical hunting ranges that he argued with ALF. Please read my previous response again slowly and concentrate.

Just put this in your pipe and smoke it , boetie:

When the .375/270gr vs .375/300 gr GSC-FN bullet was debated as to which on is better, we got this Rasputin explanation ... "With FN bullets we recommend a stability factor in excess of 2.5 for reliable linear penetration. The 300gr FN has a stability factor of 2.39 to 2.44 from 2000fps to 3000fps. Again not ideal."

How on God's earth can a stability factor between 2.39 to 2.44 not be adequate for reliable linear penetration?
To top this all of, remember we are talking here about a bullet with a considerable FN meplat !!!
Please pay attention; this is not the transition question, this is now in-target penetration, boetie !!!
This is groundbreaking stuff my friend - the kind that can only be aticulated by a modern-day Rasputin.

Remember Pieter Olivier's hunt ... the Blue Wildebeest:

The 9,3/270 GS-FN bullet loaded to a MV of 2,500 fps with a low SF of 2.09 striking at 220 yards at around 1,700 fps; it still provided straight-line penetration. No tumbling, only straight-line penetration with a small exit hole. There is no better evidence of stability than this against the bogus advice or specification of 2.5.


Then consider this:

It is not quite funny then in the light of this bogus cut-off value of 2.5, that a .366/286 gr custom turned bronze FN solid bullet (meplat = 4.4 mm), with a SF value of only 1.75, gives reliable straight-line penetration at a MV of only 2,250 fps?

Practical example - 7 x 57 mm Mauser:

I just calculated the stability factor for the .284/160 gr Barnes-TSX bullet at a twist rate of 8.66".
It pops at SF = 1.38 from 2,500 fps to 2,800 fps (at the muzzle).
And remember, the gyroscopic stability of bullet increases down range as the bullet slows down.
How ideal, anybody wanting it any different?

Please note:

a) One important note on the use of the McGyro program; it's a very common mistake to think you can calculate the downrange stability with this program. It is good for calculating muzzle stability only, even though it gives stability factors at what appear to be 'downrange' velocities, that's not the case.

b) Gyroscopic stability will generally improve as the bullet flies down range, because the forward velocity (a de-stabilizing influence) is eroding faster than the spin rate (a stabilizing influence). If a bullet has gyroscopic stability at the muzzle, it will only grow larger downrange.

Scientific basis:

On what basis should we recommend an SF of 2.5 for Solids and only 1.3 to 1.5 for Softs (ave. of say 1.4)?
Given that we deal with flight in air, i.e. air stability.
Why did Robert McCoy not differentiate between Softs and Solids?

Is a non-deforming FN Solid not more stable in target than an expanding lead-core Spitzer in target?
Why then should we specify a higher SF number that relates to air that is not applicable to flesh?
I hope you are getting my drift.

Warrior

quote:

Originally posted by ALF:
Gerard:

I'm trying to figure this out ? why would your 30 cal bullet with a S value of only 1.1 at muzzle be be a problem in hunting ?

If we calculate the SF value it becomes more stable over distance untill the bullet goes transsonic, the slower it goes the more stable it becomes as long as it remains supersonic. As a long as that bullet is statically stable it should not be a problem.

Let us see real time values for a 30 cal doing 2700 at muzzle with a SF = 1.3 at muzzle and angular velocity of 2729 rad/sec will have a SF of 2.29 at 300m doing 2020fps and 2614 rad/sec angular velocity.

The angle of attack ( SQ rt of the yaw plus pitch) of a 30 cal 168 gr match bullet at 600 m is about 2 deg with a SF value of about 3.2 So what i'm trying to figure is why you claim this to be a problem?

Gerard,

Just to remind you; this was Alf's question. Alf basically showed by way of calculation that nobody can observe small differences in angle of attack with the naked eye at practical hunting ranges and nor are they so material that one should design against its negative effect. Apparantly you can, by the fraction of degrees. And that is only so, as you are operating from 32 degrees south of the equator.

And yes, it will get worse from 500 yds out yo 1,000 yds for target shooters, as I explained explicitly.
Why engineer a condition that too high a SF must work against tractability?
Once you have sufficient gyroscopic stability it becomes a moot excercise to increase the spin further.

Warrior

No matter how much you gasp and flop around, I still see unanswered questions.

VVarior,

With 8 postings on AR your contribution to the forum is noted. On inspection, there is no substance in any of the 8 postings that anyone can learn from.

Bravo !!!


Warrior (the real one, not an imitation)

You presume much and mistakenly so. However, with your more than 975 posts, there is no substance and no replies to questions asked either.
That is a lot of posting to say zilch.

Vvarrior,
You missed one. I also asked Warrior/Truvelloshooter/Chris Bek this: "Clue: Chris, see the capital H in the circle in the formula. What do you think it means?".

Thanks for pointing out the obvious but, you are wasting your time. Warrior/Truvelloshooter/Chris Bek knows not that he knows not. As for you being accused of being me, he has done that several times in the past and been proven wrong every time. He does not learn. Anyone who disagrees with him must be me, twisting his words, knows nothing about ballistics, makes use of smoke and mirrors, hates all other bullet manufacturers and engages in Rasputinesque behaviour. Standard, hackneyed old cards he plays every time. He also repeats the same old examples over and over.


Warrior/Truvelloshooter/Chris Bek,
Let's have some fun with your plethora of mistakes, misconceptions and weird ideas.

quote:

Now most rifles in 30.06 Spr and 300 Win Mags are fitted with a barrel with a twist rate of 1 in 10"

The fact that we are discussing a 30-06 with a 1:12" twist is of no concern, you trot out examples of 1:10" 30-06s and 1:12" 308 Win examples.

quote:

This notion that terminal failures will increase when a copper mono-metal bullet goes heavier than a 140 grainer is pure horse shit.

Here are more opinions.

quote:

The reason I ask, is that I want to try the new Barnes Tippped TSX in 180 grains and they (Barnes) recommend a 1:11 or faster.

quote:

The second "failure" was a Barnes TSX that bent in a 90 degree angle after hitting the front leg bone in an average sized grizzly in Alaska. Found it under the hide on the same side in entered.

Monos bend when they are insufficiently stabilised and then tumble on impact. Not just Barnes, all makes. That is why we make the recommendations we do and why we accommodate certain elements in our designs. I do not expect you to understand this, it is a multi faceted concept and we know you have trouble with those.

quote:

I am curious to learn the cut-off SF values for the above conditions as specified by Gerard.

These have been on our website for some time now. Catch a wake up Bek. Here is an example.

quote:

It is about SF values and their specific role that is claimed by Gerard

Surely you are not that stupid. Do you really think I am the only one who claims a relationship between twist and bullet length? You cannot be serious. Have you not seen the recommended twist-for-bullet tables on virtually every barrel maker's website. The 'net is rife with examples. I have a box of Hornady V-max bullets on my load bench right now, with the recommendation to be used in 1:14"twist, printed on the label.

quote:

And then this amazing observation capability of Gerard as to the small differences in angle of attack at practical hunting ranges that he argued with ALF

Big lie!! Alf posted: "The yaw of repose of a 30 cal Sierra match bullet for a 1:10 , 1:12 and 1:14 inch barrel at 300 m is something like 0.015 deg , 0.014 and 0.013 degree." I replied: "Yaw angle on impact and the minute differences for the same bullet from different twist rates is a non-event when we discuss flat fire (say to 500m)."

I observed nothing and gave no argument. The only argument is between the little voices in your head. Of course with this, you supplied irrefutible proof that you do not begin to understand what we are talking about.

quote:

How on God's earth can a stability factor between 2.39 to 2.44 not be adequate for reliable linear penetration?

When a different specification is set, based on many hundreds of examples and two years of constant experimentation. Proof of the fact that our specs work, has been seen since 1997 in the extraordinary reliability of linear penetration that is achieved, when our guidelines are followed. Especially with the GSC FN solids.

quote:

Please pay attention; this is not the transition question, this is now in-target penetration, boetie

And therefore it has nothing to do with s/f numbers. You do have an ongoing problem with this concept, I see.

quote:

This is groundbreaking stuff my friend

Won't be the first time we have done it.

quote:

Remember Pieter Olivier's hunt ... the Blue Wildebeest:

Discussed to distraction and has only ridicule value left, because you lose every time, so here goes:

quote:

The 9,3/270 GS-FN bullet loaded to a MV of 2,500 fps with a low SF of 2.09 striking at 220 yards at around 1,700 fps; it still provided straight-line penetration. No tumbling, only straight-line penetration with a small exit hole. There is no better evidence of stability than this against the bogus advice or specification of 2.5.

Fact is that at 220 and 1700fps, the stability factor was probably way in excess of 4.0 and, despite numerous clues, you still fail to make the connection between impact speed, transition and stability factor. My goodness, I have not met another person who is slower on the uptake than what you are. That was what, three years ago and you have not worked it out yet.

quote:

It is not quite funny then in the light of this bogus cut-off value of 2.5, that a .366/286 gr custom turned bronze FN solid bullet (meplat = 4.4 mm), with a SF value of only 1.75, gives reliable straight-line penetration at a MV of only 2,250 fps?

Tested with a staggering example of three, in media designed to give straight line penetration at all costs. Good thing you are not a manufacturer - contrived examples of three mean squat.

quote:

I just calculated the stability factor for the .284/160 gr Barnes-TSX bullet at a twist rate of 8.66".
How ideal, anybody wanting it any different?

Tell that to this guy.

quote:

Scientific basis:

From you???????!!!!!!!!!!

quote:

On what basis should we recommend an SF of 2.5 for Solids and only 1.3 to 1.5 for Softs (ave. of say 1.4)?

It is a multiple concept so you will not understand, but for those who may be interested: Because solids are used at short distances and softs and spitsers are used much further out. It gets rid of the "bullet has to go to sleep" syndrome that exists with those solids that have low s/f numbers.

quote:

Why did Robert McCoy not differentiate between Softs and Solids?

But he did. You mean you have not found it in the program yet?? You have been using it for how many years since I told you where to find it? In any case, we are dealing with exterior ballistics, which requires no significant differences in how calculations are made, unless your interest is far more advanced than what you are capable of. Funny that you have not found it though. He touches on the subject in his book "Exterior Ballistics" as well.

quote:

Is a non-deforming FN Solid not more stable in target than an expanding lead-core Spitzer in target?

You have the attention span of a lightning bolt. We are discussing transition - not in target stability.

quote:

Just to remind you; this was Alf's question.

Which I answered, but you pretend you did not see the reply. You still have to answer mine but I am not holding my breath. You have no answers - have not had any for as long as you have been criticising GSC bullets. We have an extraordinary record of successes which is obvoiusly galling to you and your agenda.

quote:

Alf basically showed by way of calculation that nobody can observe small differences in angle of attack with the naked eye at practical hunting ranges and nor are they so material that one should design against its negative effect. Apparantly you can, by the fraction of degrees.

So you repeat the lie. Hoping it will somehow become true? Stupid is as stupid does.

Now let's see if you can muster the intelligence to respond coherently to:

1. Chris, see the capital H in the circle in the formula. What do you think it means?
2. Who manufactures a hunting bullet, that flies with its nose up at hunting ranges of 200 to 500, with a muzzle s/f of 5?
3. It would be interesting to see what you would offer as proof of this "myth" of transitional stability? Some research perhaps, or some comparative testing? Maybe another's noted opinion based on a smidgen of research or testing?
4. Forgive me for adding a fourth question that you cannot answer: With this imaginary bullet in question 2, what would the angle of departure of the bullet axis be, compared to the line of sight, for a 500m zero? You know, give us some idea of how terribly "nose up" such a bullet would fly on its way to the 500 mark.



You were reminded previously of Dr. Ken Oehler's signature line but you would do well to check it out again.

quote:

As it was explained to me many years ago, "I feel sorry for those who think ballistics is an exact science. They just don't understand the problems."

Thank you for supplying light entertainment this Monday afternoon.

What a lot of smoke this is - skewed, incoherent and mostly irrelevant.
An absolute waste of time, running in never ending circles.
Rasputin stuff.

Cheers
Warrior

I suppose that is as good a reply as any.........when you don't have any answers. Gerard, I see what you mean by the usual cards. Smoke, skewed, never ending circles Rasputin........and no answers.

/

Alf,

Thanks for your reasoned and informative reply, a scarce commodity here on AR, especially on this thread.

I used the SF=5 bullet example merely as indicative of an extreme example of over stabilization at the muzzle (not a specific bullet), very much in line with CZ's move to fit a 9" twist barrel to 9,3x62 mm. As I indicated it is an engineered condition in the believe that it is better than the traditional recommendation of SF = 1.3 to 1.5 at the muzzle for hunting purposes. Various pundits propagate faster twist rates and lighter bullets as they chase velocity, as it apparantly favours the FN design (new scientific discovery ) New rules if you will. I questioned CZ's move on this issue, but Gerard worshiped this idea and took me to task as if that was the right thing that CZ had done.

How can an SF = 5 be achieved - by fitting a 9" twist barrel to a 9,3x62 instead of the standard CIP spec of 14".

Details:

Bullet type 320 gr Wdl SN
Bullet diameter .366"
Bullet length 1.323"
Nose length .315"
Meplat .118
Jaketed lead-core for specific gravity constant
Twist rate of 1 in 9"
Tangent ogive
Flat base bullet
SF value = 4.67 for typical velocity of 2200 fps
Use Wdl lighter/shorter bullet of say 286 gr and SF will go to 5.85

More extreme conditions can be engineered with a .458 caliber to fit a 10" twist instead of a 14" twist, and again we go with a light for caliber bullet. Play around with 350 gr Hdy FP bullets, 400 Gr FN bullets and 450 gr FN bullets to see what SF values you hit.

Side note - the 45-70 Government has a CIP recommended twists rate of 20" and the 350 gr Hdy FP is commonly used, but Garrett made heavier bullets for it such as 420 and 540 grainers (hard cast bullets), without fitting faster twist rates to the rifle. These heavier bullets bring the SF values down. If we now fit a 10" twist barrel, like some recommend for the 458 Lott, then the SF values will shoot up. I am sure Garrett did it to get momentum values up in the system and sacrificed velocity for better penetration.

We see similar proposals to fit 10" twist barrels to the 404 Jeff and 416 Rigby, when the CIP spec calls for 16.5" Drastic changes. And this begs the question ... is this advisable? What are the pro's and con's, and it is for us to consider.

Warrior

quote:

Originally posted by VVarrior:
You presume much and mistakenly so. However, with your more than 975 posts, there is no substance and no replies to questions asked either.
That is a lot of posting to say zilch.

So true...

977 post when I typed this, and not a word he hasn't later contradicted himself.

JPK

.

Alf,

Correct, I did not specifically refer to .30 cal bullets. I made a general point that additional twist was superfluous, once sufficient gyroscopic stability was achieved. And that such a condition of over-stability could work against tractability.

One such move was by CZ lately by fitting a 9" twist to their 9,3 x62 mm. Who knows what they may do next, or what custom fittings may be ordered by customers. The same can be done for the 375 H&H to have a faster twist barrel fitted. Lutz Moller is already making a 150 gr bullet for the 375 H&H? What would the SF value be here, not sure, as I don't have a bullet to calculate its SF value, but it will be very high and the intention here is to chase a light bullet with lots of powder behind it, and presumably it is intended for long-range. Although high in SF, it will not buck the wind real well, as it is light for caliber (.375/150 gr), and so its low sectional density will bring the BC down, even though it is a Spitzer bullet.



I concurred with you when you said and you asked what was wrong with a SF of 1.3, as was generally recommended for hunting ... "Let us see real time values for a 30 cal doing 2700 at muzzle with a SF = 1.3 at muzzle and angular velocity of 2729 rad/sec will have a SF of 2.29 at 300m doing 2020fps and 2614 rad/sec angular velocity. The angle of attack ( SQ rt of the yaw plus pitch) of a 30 cal 168 gr match bullet at 600 m is about 2 deg with a SF value of about 3.2 So what i'm trying to figure is why you claim this to be a problem?"

The other bone of contention was that a higher SF value would assist the transition stage from air to flesh, and that was claimed as its redeeming benefit, after Gerard relized that in-target penetration was not governed by SF, but by geometry of the bullet as you have explained very well. Then he switched his story to the transition theory. In my above post you can see, and I quote the position he once held ... ""With FN bullets we recommend a stability factor in excess of 2.5 for reliable linear penetration. The 300gr FN has a stability factor of 2.39 to 2.44 from 2000fps to 3000fps. Again not ideal."

Alf do you have a program that works out the 'yaw of repose' and the 'bullet pitch' (tractability condition) at various ranges, or do you calculate it by way of formula long-hand? And the same applies for the SF value down range, as the WinGyro pragram cannot do it for us.

Appreciate your comments.

Warrior

Warrior/Truvelloshooter/Chris Bek,

You are probably the most accomplished person at making an ass of yourself I have ever met.

quote:

The other bone of contention was that a higher SF value would assist the transition stage from air to flesh, and that was claimed as its redeeming benefit, after Gerard relized that in-target penetration was not governed by SF, but by geometry of the bullet as you have explained very well.

The first time Alf and I discussed stability in flight and in tissue and bullet geometry was somewhere during 2005 I think. Here are some posts of mine that date back to 2001 where I mention the relationship between gyroscopic stability (the product of bullet length, shape and twist rate) and linear penetration, shoulder stabilisation and cavitation.

quote:

Posted 28 April 2001 19:49
ensure firstly that the correct length of bullet is chosen rather than a particular weight. Performance will improve if this is done.

Posted 16 June 2001 10:21
If the two bullets are identical, and the ballistics are the same except for the twist, the bullet spinning faster will penetrate straighter.

Posted 05 October 2001 11:29
You will find that increasing "d" to 6 mm and turning a 2mm radius on the edge to bring 3/4 to 2mm, will improve penetration even more. This will reduce the nose angle off axis as well as reducing the overall length, further increasing the resistance to tumbling within the target. On our FN bullets we use a conical ogival shape and the penetration results are exactly as you describe for the SP. We dispensed with the use of a hard insert in the nose of the bullet as we could not prove any difference in penetration with the shape machined directly on the copper or as a two piece bullet. In some cases, when extreme stresses were imposed on the test bullets, the harder material insert led to a catastrophic failure of the bullet as a solid.

Posted 12 October 2001 08:25
Linear penetration has very little to do with sectional density. It has everything to do with bullet shape after impact, momentum and energy.

Long for caliber bullets have a reputation for bending and turning and even complete failure if driven hard enough, and I will take a shorter bullet for linear penetration any day. I have done a small amount of experimentation around this subject.

Posted 29 October 2001 09:57
Logically, if the twist rate is fixed (you have bought the rifle), penetration will be more reliable with bullets shorter than what is required for stable flight. Bullets with too little gyroscopic stabilisation will not always tumble on impact, but using slightly shorter bullets than required, is good insurance against that kind of failure.

Posted 20 November 2001 17:53
We are assembling our buffalo box for testing the 300 gr HV / FN, but if my 375H&H bends one of them, they are history.

Posted 26 November 2001 03:39
When using monometal bullets, the weight should be reduced to keep the relationship between twist and bullet length. So if heavy for caliber monos are used, say a 180 gr in a 308, the bullet is highly prone to tumbling on impact resulting in much bruising and unpredictable behaviour. This is why we steadfastly recommend light and fast monos. They are better after impact that way.

Posted 29 November 2001 18:41
The combination of retained momentum and energy, frontal area and deformed nose shape determines how a bullet works on game, nothing else.

Posted 27 December 2001 10:56
The tighter twist will increase the gyroscopic force that holds the bullet stable on it's axis. It is less prone to tumbling or veering off line in the target. it makes for more reliable terminal performance.

Your inference that you or Alf "explained" the dynamics of bullet geometry during penetration to me is truly funny. I designed the FN range with its shoulder stabilisation in 1996/7. The first time Alf mentioned shoulder stabilisation on this forum was about 2005 or 2006, more than eight years later. It shows just how much you think you know.

In 2001, after five years of watching how FN bullets work, it was my observation that there is a strong relationship between s/f and linear penetration. I did not know why it was so at the time but, as I have often said, when we see a design direction improves a result, we follow that direction and figure out why afterwards. I now have further 8 years worth of experimentation and observation of the relationship between s/f and linear or non-linear penetration under the belt.

Now I have formed some opinions on the subject. I back my opinion with 13 years of experience of the subject. What do you have to back up your opinion? For the last 17 years I have lived and breathed bullet design and performance every day of my life. What is there that you think you can tell me? You are a crackpot and you have amusement value only. There are many, many people I can learn from - you are not one of them.

quote:

Then he switched his story to the transition theory.

Unlike you, I do not switch my story to whatever crackpot idea is the flavour of the day. I have said in the past that you are incapable of learning and this proves it beyond doubt.

I have been discussing the transition/stability issue for more than five years and not just here on AR. I research and put forward theory and discuss with those who can give answers and who have greater insight and knowledge. The fact that you question it now, with no better substance than "horseshit" and an agenda, shows your dismal lack of development.

You are an amusing buffoon if nothing else.

Alf, I have a question:

Why does a short bullet arrive at the target at 1000yds with its nose up, while a longer bullet of similar construction, fired from the same rifle, arrives more nose on?

quote:

Posted 27 December 2001 10:56
The tighter twist will increase the gyroscopic force that holds the bullet stable on it's axis. It is less prone to tumbling or veering off line in the target. it makes for more reliable terminal performance.

Gerard,

It is not the increased SF, it is the geometry of the bullet that governs in-target penetration.
SF is simply a statistic that relates to air.

Warrior

one of us
Posted 26 August 2005 10:56 Hide Post

Gerard,

Quote:

"With FN bullets we recommend a stability factor in EXCESS of 2.5 for reliable linear penetration. The 300gr FN has a stability factor of 2.39 to 2.44 from 2000fps to 3000fps. Again not ideal." .... Gerard Schultz.[/color]

Reply:

I think you are the one that is hyperventilating instead of me. Let me tell you straight ... YOUR THEORY ABOUT THE 2.5 SF IS BULLSHIT !!! Please dish it up for the kids at your local kindergarten. The above bullet will be stable at the low velocity of 2,000 fps at an SF value of 2.39. If we need a value in EXCESS of 2.5 on a FLAT NOSE, then we should have seen great chaos over the last hundred years with big game hunters using RN FMJs - but we did not !!!

Warrior

Why does the FN design give deeper straight-line penetration in target at the same weight and velocity? It is simply so because of geometry, the FN bullet better damps out the angle of attack effect in target and it has shoulder stabilization. It is not the spin rate.

Warrior

Warrior/Truvelloshooter/Chris Bek,

You are a pissant amateur with delusions of grandeur.

quote:

it is the geometry of the bullet that governs in-target penetration.

That is what I said 8 years ago: "Posted 12 October 2001 08:25
Linear penetration has very little to do with sectional density. It has everything to do with bullet shape after impact, momentum and energy."

quote:

I think you are the one that is hyperventilating instead of me. Let me tell you straight ... YOUR THEORY ABOUT THE 2.5 SF IS BULLSHIT !!! Please dish it up for the kids at your local kindergarten.

That and "horseshit" is all you can offer to counter 13 years of single minded research of the subject. You cannot even make up your mind over the type of excrement you offer as argument. Pitiful.

quote:

the FN bullet better damps out the angle of attack effect in target

Making up terminology on the fly again. Gooooogle is a dangerous tool when you find things you have no clue about and you are incapable of learning.



Why don't you have a go at the question I asked of Alf? That should be good for some entertainment.

quote:

quote:
the FN bullet better damps out the angle of attack effect in target

quote:

Making up terminology on the fly again. Gooooogle is a dangerous tool when you find things you have no clue about and you are incapable of learning.

Gerard,

This is not googled nor made up on the fly, but in fact echoed by Alf himself !!!

Your compliments are never ending. If you think you can score points like this, then you are mistaken. All you try to do is to elevate yourself. Nobody has a clue and is capable of arguing with you. This line is getting boring now.

Thanks
Warrior

quote:

Why don't you have a go at the question I asked of Alf? That should be good for some entertainment.

Gerard,

Regarding the question that you posed to Alf ..... are you asking a question of which you known the answer?

If so, why do you ask it then? Is it about trickery or what?
Why can't you just share the the answer with us, or guide us and instruct us through this difficult question?
That would have educational benefit.

If the answer is not known to you, why then frase the question as a statement of fact?

I can only conclude in the face of the above, that it is about trickery and an alterior motive.
Never straight, always a diversion. But you expect a straight answer from Alf?
Your agenda is transparent, wheras Alf always shares his knowledge in great detail.

Warrior

quote:

Alf always shares his knowledge in great detail.

Alf can do so simply because he doesn't operate a business with patented designs, skills and knowledge like the ones Gerard has to protect from prowlers like yourself continuously searching stealthily for new ideas that you can't generate from within.

quote:

Alf always shares his knowledge in great detail.

Ah well....er....ah...that's one way of saying it!

He could have merely said that from his own personal studies a 1-12" .30 caliber twist works just fine....instead it's not exactly clear just what he is saying!