Has anybody noticed that, within a given rifle, the higher the Sd goes, the more yaw the bullet has. (Yaw, for the purpose of this discussion being, fast and slow precession, nutation, coning motion, pitch and all the stuff that makes it point away from the line of flight.) If yaw is bad, is high Sd bad?

Are we back on a twist thread?

I've had Serria 250 gr BT bullets out of my 338 RUM fill a one foot circle at 200 yds. But at 400 yds those same bullets did a little stringing with out making a circle. Is this Yawing at 200 yds?

Since my name got bought into it...

I use woodleigh 286grn solids for elephant. I have tried the 320grn and they penetrate significantly less than the 286's if a leg bone or skull is hit.

When doing some load testing for Norma's new PH line of ammo we issued some for the last two proficency exams. The 450grn Barnes Banded solids out penetrated the 500 grn Barnes Solids on head shots. Norma went with Woodleigh solids in the end.

All bullets yaw (helix) - shott a tracer into the night sky and watch, or shoot a bullet through an elephants front leg (when fresh) and dissect. If the exit hole is round- the bullet is stable. Many are oval Art Alphin intially started out with 480 & 500grn monolithics when he was designing his A square rounds (in .458) after much experiemnting he came down to 425, 450, and 465 grn mono's. He and mike la Grange settled on 465grn as giving the best penetration out of a .458 with his bullets.

Ganyana,

What is the velocity of your 320 grainers in the 9.3X62?

465H&H

quote:

Originally posted by Ganyana:
Since my name got bought into it...

I use woodleigh 286grn solids for elephant. I have tried the 320grn and they penetrate significantly less than the 286's if a leg bone or skull is hit.

When doing some load testing for Norma's new PH line of ammo we issued some for the last two proficency exams. The 450grn Barnes Banded solids out penetrated the 500 grn Barnes Solids on head shots. Norma went with Woodleigh solids in the end.

All bullets yaw (helix) - shott a tracer into the night sky and watch, or shoot a bullet through an elephants front leg (when fresh) and dissect. If the exit hole is round- the bullet is stable. Many are oval Art Alphin intially started out with 480 & 500grn monolithics when he was designing his A square rounds (in .458) after much experiemnting he came down to 425, 450, and 465 grn mono's. He and mike la Grange settled on 465grn as giving the best penetration out of a .458 with his bullets.

I was confused by the staement that a lighter bullet penetrates more.If one shoots them at higher velocities then that is another story.

quote:

Like the word Ho or Hoe as used in context of descibing the members of a certain basketball team..... I for one had no clue there was even such a word, the Oxofrd dictionary does not list it but the "Urban Online dDctionary " certainly did and now I understand too why some may get upset about being called a "hoe"....... problem is I fail to see what racial connotation is aplicable to the word as nowhere is race defined by that word? Hnece then no undertanding why the Rev Jesse jackon and One Al Sharpton may what to get invloved

I think this thread developed a YAW.

465- Got the woodleigs to 2100fps and the 320grn mono's to 2000fps.

The 320grn bullets worked a treat in Charlie Haleys 400/360 -W-R double though and one of the other lads has a lovely farqueson in .360 No 2 which also does well with the 320grn woodleighs

Ganyana,

Just for the sake of comparison with if you achieve 2000 fps with the 320gr Wdl FMJ. Let us pick the middle load (not the compressed on) for the 286 Wdl FMJ which you loaded before:

[Quote]Norma Brass, CCI 250 magnum primers, 24" barrel, Woodleigh 286grn Solid, seated to cannelure (82mm), Air temp 36°C (97F).

58grns = 2341fps
58.5grns = 2360fps
59 grns = 2390 fps[quote]


Momentum = 286gr/7000 x 2360 fps = 96.4
Momentum = 320gr/7000 x 2000 fps = 91.4

If you make up the load this way, then your observation seems to come in line with Mo/Xsa, and if there is a wobble present in addition with the longer and heavier bullet, then increased drag will take its effect as well and compound the result.

When Pieter Olivier and myself developed 9,3 loads we got 2123 fps with the 320 gr bullet (50.5 gr S341, CCI250, PMP cas, AOL=82.5 mm) This translates to 97.1 Momentum. Our favoured load with the 286 gr bullet got 2257 fps (58gr S355) and that yields 92.2 momentum. So the way we make up the load will influence the result, but the interesting phenomenon to explore is if there is indeed increased wobble with the heavier bullet that hampers it by virtue of a too slow twist.

Making comparisons of bullets where the one is not stable and then blame SD (like some would be inclined to do) for it is like throwing diesel in one's car when in fact it was designed for petrol and then ...


Warrior

quote:

In softs, I have found that the Woodleigh 320 penetrated deeper than the Woodleigh 286. It also expanded less (lower velocity). I was going to perform an experiment on ele to see whether the 286 or 320 solid penetrated further until my friend told me he had already done it and the 286 was the clear winner. The subject was elephant. However, I did not get data from him so I have nothing to repeat here.

Dan,

So we now sit with this dichotomy. Opposing results for Softs & Solids. It is worth exploring further. At this stage it seems we blame the wobble in the heavy Solid (320 grainer) but it is not a factor in the Soft?

Warrior

Hi Warrior

Doing the maths ... I wonder... I only ever tried the 320grn woodleigs in my Model A Mauser. With my new Dumoulin with a tighter twist

I know Kevin Robertson (and 465H&H) like the 550grn woodleighs in the .458 Lott as they seem to hit "harder" than the 500grn. A little bit of wobble/fistailing will undoubtably increase this "clout" just like a big meplat does.

On the proficiency exam we were only looking at penetration and bullet deformation with the Barnes bullets, not percieved knock down power.

Bullets that "fail" most certainly do increase knockdown effect. We often saw this on the buffalo erradication culls with the guys using .404's. We were issued with old RWS solids and on average the jackets tore open and they tumbled. Worked as well as any premium soft on buff! But the guys who had .404's would only use their carefully horded stocks of Kynock solids for elephant as the RWS ammo was too unreliable for a frontal brain shot. ( RWS now load woodlieghs).

I have always been more concerned with straight line penetration than "knock down" effect - on elephant. Rightly or wrongly I belive that if i need more clout I should use a bigger rifle rather than trying to wring more out of a small bore - I see no point in loading a .375 up to 2650fps as some lads do here. If the regular .375 isn't good enough just buy a .404 or 416!

Which is exactly why the .458 Lot comes out if I have to venture into the jesse or for crop raiders at night in the thick stuff.

quote:

You may want to consult some people that have actually used the 320 gr Woodleigh.

It was introduced exactly for the purpose of improving on penetration over a 286 gr projectile.

NitroX,

I think we are back to the above statement ... somebody that has used the 320 gr Solid of Woodleigh extensively.

I have only shot it from the bench for safe load development, and not to check its terminal effect on game. There may be some Australian water buffalo hunters that can shed some light on the subject.

Warrior

quote:

Originally posted by Warrior:

So we now sit with this dichotomy. Opposing results for Softs & Solids. It is worth exploring further. At this stage it seems we blame the wobble in the heavy Solid (320 grainer) but it is not a factor in the Soft?

Warrior

Chris, when we want maximum penetration we use a solid. A soft is not designed for maximum penetration and the best soft does not necessarily penetrate the maximum depth.

Also, I think you posted before that when a soft opens up, its length is reduced so that overlength should not cause stability problems. If I paraphrased that incorrectly, please clarify. Personally I do not know if that is true or not. But I did notice that 320 9.3s were not as accurate as 286 gr 9.3s.

quote:

Chris, when we want maximum penetration we use a solid. A soft is not designed for maximum penetration and the best soft does not necessarily penetrate the maximum depth.

Also, I think you posted before that when a soft opens up, its length is reduced so that overlength should not cause stability problems. If I paraphrased that incorrectly, please clarify. Personally I do not know if that is true or not. But I did notice that 320 9.3s were not as accurate as 286 gr 9.3s.

Dan,

You are right, I can't argue with this. It is just that I do not know enough about the Wdl 320 grainers. Personally I am quite happy shooting Rhino's Soft 286-gr Semi-Spitzer, as my preferred bullet, and I cannot see the need for going up to the heavier 320 grain Soft or Solid.

warrior

Do bullets yaw?
Yes, until they "settle down". All bullets of all shapes and sizes. going from a controled confined space (barrel) to an uncontroled atmosphere. (outside the barrel)
That's all I can offer, which ain't much! Trying not to start anything but twist has a lot to do with it.

/

The puzzling thing is that the lead-core Wdl 320 FMJ is a perfectly stable bullet, as supported by a SF value of 1.45 (more than stable in air), which is so close to the generally accepted and thrown around statistic of 1.5 being ideal. So why should it exibit excessive yaw?

The 286 gr Barnes Solid (made from brass) has an even lower stability factor of 1.36 and the longest bullet of all, the 286 gr Barnes-X bullet (made from copper), has a stability factor of 1.28.

Thus to solve this conundrum, I think all bullets should be tested under the same conditions before we can categorically say that due to the excessive/greater yaw of 320-gr bullet vis-a-vis other bullets, it penetrates less.

As Alf says all bullets start off with a yaw and then settles down range - the only thing is we do not know exact distances and how critical it is at distances under 15 or 25 paces.

Warrior

/

Alf,

It makes sense that a bullet's penetration would be negatively affected if it strikes at an angle of attack. Why should the 320-gr Wdl FMJ bullet have a greater angle of attack than the equivalent 286-gr bullet - purely because of bullet length, which differ by 3.5 millimetres? In other words, explain which factors govern this angle of attack thing or incidence.

The basic premise is that if these 2 bullets are loaded to the same momentum, and they are very close in deed in this particular case, then they should penetrate the same depth based on Mo/Xsa, despite different SD values. However we now have to deal with this factor of "angle of attack" that will influence the result.

Please explain, even though some say that once you have answered the question, we understand the question even less. This comment was indeed amusing.

Warrior

quote:

Originally posted by boom stick:
if i read his post correctly the question is does the bullet "true" itself in the beginning of its flight.

Yes, it does, but the distance downrange it takes for this to happen varies depending on length and configuration of the bullet and spin rate. For example, it takes the U.S. cal .30 M1 173-grain boattail about 200 yards to settle down when shot from the '06 at 2600 FPS and 1/10" twist rate. The term "going to sleep" has been applied to this phenomenon.

/

So i got an box of 400 grain Barnes solid RN style yesterday, will they work good or will they be like flipping an coin on an Loxo`skull in a few months time?

I have used abit bullets in the 450 NE Straight in the Ruger nr 1 , and they have shown that it can vary how long they are with variabel stabilization and as then variable penetration.

I`have got advice on to load the 450 with 550 grain Woodleigh at 2100 fps and it will be tried soon to see how it performs.

But many has proven that there is one reason why many still uses the good old bullet style for various calibers that its weight was originally made for them.

They work and they dont Yaw.

Mr Rigby,


The Barnes solids are overly long and may tend to be unstable. I would suggest switching to Woodleighs in that bullet weight.

The Barnes solids are not "overly long". They will stablize just fine. Rifling is based on bullet weight not length.

quote:

Originally posted by Buliwyf:
The Barnes solids are not "overly long". They will stablize just fine. Rifling is based on bullet weight not length.

Nope.

Yep.

Nope.
The majority will agree with Dan on this one, for a change!
You cannot change physics by being a bully.
Rifling is based on bullet length not weight, to paraphrase.

Those brass Barnes "banded" solids are even longer than a denser copper solid of same conformation.

Whether that is too long or not might be debatable. But not debatable is the weight versus length determining required twist.

Rifling is based on bullet WEIGHT!!

/

Rifle barrel twist doesn't know OGIVE length from tip!!!!!! Projectile WEIGHT is what determines correct twist!!!!!!!!!!!!

I don't know who you are or who Dan is, but physics can't be changed by you or any other bully!!!!!!!!!!!!!

Alf:

My last post went through at the same time as yours.

http://www.rhinobullets.co.za/buffalo.htm

so what twist for the 380 grain 375 rhino bullets? 1 in 10?

Well Greenhill Formula be damned! And me too! I beg your pardon, Buliwyf.

boom stick,
I am at a total loss now.
Formerly I would have asked you for the length and caliber of the bullet, regardless of its weight, and plugged into:

T = 150(d^2)/L for 1500 to 2800 fps bullets
0r
T = 180(d^2)/L for bullets over 2800 fps

Where T = twist rate in inches
d = bullet diameter
L = bullet length

Once again I have proved myself an ignorant caveman.

/

Alf,
Holy gyrating nutating wobbles!
So Greenhill goes south for anything less dense than jacketed lead?

Would not the longer brass bullet be less stable, assuming nondeforming solids, than progressively shorter bullets of same weight made from copper, lead, tungsten, depleted uranium, and unobtanium?

I have never been able to download the software for stability factors, and lack the patience to look any further, other than the education I get here.

The overturning moments of the bullets are greatly increased by bullet length aren't they, by distance of the leading edge and base from the center of gravity?

/

As in Greenhill, diameter squared divided by length, no bullet weight considered in the limited situation of sporting rifle bullets ...

For practical purposes Greenhill still seems to apply to length of bullet relative to its diameter with a constant and a fudgefactor for velocity.

No bullet weight needed.

quote:

For practical purposes Greenhill still seems to apply to length of bullet relative to its diameter with a constant and a fudgefactor for velocity.

The fudge factor of Greenhill used also incorporated a Specific Gravity element of 10.9 for the jacketed lead-core bullet in use at the time. That is why it goes south if we use surgical cotton balls. That is why we cannot use a percentage as some suggest of around 6% [150/.06 = 2,500] or [180/.06 = 3,000] or any other percentage.

Warrior

Click here for a bullet length / twist calculator that works. Select "Save to disc"and then click on OK. The downloaded file is called wload212.zip. Open it and run the winload.exe file. Use the WinGyro section for stability calculation.

quote:

Why should the 320-gr Wdl FMJ bullet have a greater angle of attack than the equivalent 286-gr bullet - purely because of bullet length, which differ by 3.5 millimetres?

The short answer is: An increase in sectional density allows the slow precession of the bullet to persist for longer. The shorter bullet will therefore strike at a lower angle of attack closer to the muzzle than the longer one if both are of similar specific gravity.

quote:

Rifling is based on bullet weight not length.

I suppose one can make a case for that statement on paper and probably prove it mathematically. You would have to vary the diameter to do so, I think. In practise that is not what is being discussed because the comparisons are between different weight bullets of the same caliber or different length bullets of the same caliber. So a practical comparison of bullet lengths of the same caliber shows:

Caliber - Weight - Twist rate - Bullet length - Stability Factor - Shape
270 ----- 150gr -- 1:10" ------ 31.2mm/1.23" - 1.44 @ 2600fps -- SP BT
270 ----- 150gr -- 1:10" ------ 26.8mm/1.06" - 2.07 @ 2600fps -- RN FB

A stability factor of 1.5 can be had with the Round Nose Flat Base bullet in a twist rate as slow as 1:11.3" while the same weight Spitser Boat Tail needs a twist of 1:9.5" for a stability factor of 1.5.

The RN FB bullet will be more inclined to give linear penetration at close range because both precession cycles are less to start with and, what precession there is, dampens more quickly. The lower angle of attack and higher stability factor at impact improves the successful transition from flight to tissue with less inclination to turn sideways. This example applies to similarly constructed jacketed lead bullets and cannot be used to compare expanding jacketed lead to expanding monometallic bullets.

An interesting thread anyway. Not knowing the math, I cannot say anything about yaw from the technical point of view, however, as a practitioner I would like to add that we used to watch .30-06 and .308 match bullets in yawing flight years ago when I was a serious Navy Match shooter. With the sun at the right angle and when you were sitting behind the shooter as a spotter with a 20 or 40 power scope, the yawing bullet was easy to see.
LLS