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It does appear that most here prefer bashing Muleskinner rather than anything meaningful -- so the following is for the minority of you all who're interested in technical matters.

The question was asked so long ago that I don't remember who asked it or even on which board, but here's the answer as provided by Mathcad 8 Professional and the mistakenly maligned classic Greenhill equation.

The question -- what's the best twist for stabilizing the 75-grain Hornady A-Max .224 bullet?

The equations -- minimum (shortest) twist = 150 times the diameter of the bullet, squared, divided by the length of the bullet
-- maximum (longest -- usually optimum) twist = 200 times the diameter of the bullet, squared, divided by the length of the bullet

After much diddling around getting acquainted with the complexities of Mathcad 8, I finally learned how to feed it the right flavors of the math for my old unproductive file on the Greenhill equations. My reward: the minimum and maximum twists for a .224 bullet 1.105 in. long:
minimum 6.811 inches (6.9 or 7 inches)
maximum 9.082 inches (9 inches)

A 7-inch twist (a) overstabilizes the bullet at any velocity and (b) overspins it at top velocities available in the .220 Swift, .22-6mm, and .220 Howell. At best, a 7-inch twist limits the top velocity that doesn't tear the 75-grain .224 A-Max apart just beyond the muzzle.

A 9-inch twist lets the 75-grain .224 A-Max hold together at higher velocities but requires a higher-quality barrel. (The Richards barrel on my .220 Howell, for example, is a very smooth three-groove barrel with a nine-inch twist.)

For lesser-quality barrels -- or barrels of unknown or unproven quality -- an 8-inch or 8�-inch twist is probably the practical maximum.


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Ken this info seems to be correct. In fact it's that bullet that was the last straw for my worn .224 Magnum 1-9 barrel. The bullets tipped just a little and buck shot the 100 yd target. Since the Douglas Premium barrel has over a thousand shots thru it and the cartridge holds 57 grs of water it's no wonder that it's soft.


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Ross Seyfried proved some time ago that "over stabilization" is a load of hooey.With a 1-in-8 twist,30 inch barreled 22-284,he was pushing the little Nosler 60 grain Partition 4200 FPS,and shooting way under 0.5 inch at 100 yards.It retained it's accuracy out to 800 yards too.

WB.


"You set your own goals for success, and when you succeed it don't necessarily mean that you're going to be a big star or make a lot of money or anything. You'll feel it in your heart whether you've succeeded or not." - Roy Buchanan
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Loss of accuracy is not the problem with overstabilization, which has been thoroughly proved by classic (but simple) experiments and extensive field observations well beyond anything that Ross Seyfried is likely to have done to study the concept.

Overly stable bullets don't tip nose-down as their trajectories arc over and start dropping. This means that as it travels, the overly stable bullet flies less and less point-on, more and more nearly sideways. (I'll look to see whether I can resurrect and -- later -- post a couple of drawings that illustrate adequate and excessive stabilization.)

At extreme range, it falls to a horizontal surface with its point still higher than its tail, at very nearly the same nose-up angle that it left the muzzle. It may still be grouping well, but that's another matter altogether.

What matters is that the overstabilized bullet (a) loses velocity faster and (b) consequently has a much shorter practical range than the same bullet just barely (but adequately) stabilized.

IOW, the field-derived de facto ballistic coefficient of the overly stable bullet is lower than it would be if the bullet were only border-line stable -- just stable enough (and just nearly unstable enough) to fly its entire trajectory point-on

Thanks for posting your reminder that shooters, readers, writers, and editors need a better understanding of ballistics!


"Good enough" isn't.

Always take your responsibilities seriously but never yourself.



















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Well,what your saying doesn't sound correct to me,but I'm too ignorant in that field to counter with anything,so once again,I bow to the master......

WB.


"You set your own goals for success, and when you succeed it don't necessarily mean that you're going to be a big star or make a lot of money or anything. You'll feel it in your heart whether you've succeeded or not." - Roy Buchanan
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This ought to do it --

[Linked Image]

[Linked Image]

[Linked Image]


"Good enough" isn't.

Always take your responsibilities seriously but never yourself.



















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Tried to fix it,couldn't.Me thinks you done something wrong,either that or something in the system is FUBARed.

WB.


"You set your own goals for success, and when you succeed it don't necessarily mean that you're going to be a big star or make a lot of money or anything. You'll feel it in your heart whether you've succeeded or not." - Roy Buchanan
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I KNOW I did something wrong.
Don't know WHAT.


"Good enough" isn't.

Always take your responsibilities seriously but never yourself.



















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W
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Testing for Ken
I don't know what is wrong either. I can cut and paste and make it work, but can't make it post??? <img src="/ubbthreads/images/graemlins/confused.gif" alt="" />
[img]http://www.imagestation.com/mypictures/inbox/view.html?id=4235805702&url=http%3A%2F%2Fwww.imagestation.com%2Fpicture%2Fsraid56%2Fpf65f33287877e4cfbd02d7fd9a427cce%2Ffc794406.jpg&caption=overstab[/img]

Last edited by Westman; 03/20/03.
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Check your e-mail, Bandit.
You should have the three drawings there.
Let me know if you don't, and I'll try another way.


"Good enough" isn't.

Always take your responsibilities seriously but never yourself.



















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Ken,
Got them all,and responded.Thanks kindly.I actualy learned something today for a change. <img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

WB.


"You set your own goals for success, and when you succeed it don't necessarily mean that you're going to be a big star or make a lot of money or anything. You'll feel it in your heart whether you've succeeded or not." - Roy Buchanan
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Finally fingered it out. Go back up & have a look.
How 'bout deleting the long string in your post -- please? That should then reduce the width of this thread to screen width and make lateral scrolling unnecessary.


"Good enough" isn't.

Always take your responsibilities seriously but never yourself.



















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Ken, that was a GREAT post, and the diagrams made absolute sense. For the first time now, I understand understabilized and over stabilized. Thanks for the clear and concise answer.


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Have had fairly good success with the 60gr Vmax in my 22-06 w/ 28" Douglass 1x10. Thus far, 53grs of H4831SC will put 5 of them into a tad less than 3/4 inch at 100yds, but I haven't really gotten into much load experimentation yet.
The friend that put the barrel on, said he shot the tightest groups with the 65gr JLK and 55grs of that powder in my rifle, but they've been "out of stock" since last fall. IIRC, velocity was somewhere's in the high 3800's.
He shot a variety of bullets/loads in my rifle and it didn't much like anything over 65gr, although HIS 22-06 w/ 1x9 Douglass will shoot 70 and 75gr bullets very well.

Knox seems to be concentrating on the heavier .224 bullets since last summer, as I check OK Weber's site frequently and the lighter .224 bullets are always unavailable.


If three or more people think you're a dimwit, chances are at least one of them is right.

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