quote:

copper Cup Point

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Originally posted by RIP:
Mike,
That would be .474" then, for safety in double rifles.

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Originally posted by michael458:
Now, I did some 9.3 tests a couple of months ago, some have seen them, I posted over on my 9.3 thread on small bores, or somewhere. I am bringing them here today since I have nothing else to offer, and there may be some lurkers here that did not see them.


Want to talk about good penetration!

Michael

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His partner says, 'Ya know, I'd heerd of that there 'Hind Lick Maneuver' but I ain't niver seed nobody do it!'

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The Cup Point is a deep penetrating soft or a shallow penetrating solid, that stays straight-on-course.
Puts more hurt into its shorter course in a buffalo.
Not meant for elephant braining, but would work most of the time there too. Eeker

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Originally posted by michael458:



Michael

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Originally posted by boom stick:
If you look at the "Round nose" of the woodleigh you can see that the front of it is not round but a hybrid flat/round nose

quote:

Originally posted by michael458:
Mike

My last tests with the 470s almost 4 years ago were as follows;

500 gr Woodleigh FMJ
50 Yard Impact Muzzle velocity 2172 fps
20 inches straight--tumbled, turned and veered until they were found completely backwards at 26 inches total. 3 of these were done, exact same results.

500 gr Barnes Round Nose
50 Yard Impact Muzzle Velocity 2147 fps
24 inches straight-veered off course left the box at 34 inches. X3, same results.

22 inches straight-veered off course left the box at 32 inches. X2, same results.


Michael

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Originally posted by boom stick:
Funny joke there Rip

I have a test medium thought

would not two 3/4" high grade plywood clamped or glued together simulate the toughest of buff bone?

If so then you can see the bullet path and depth of penetration by having a few inches of some kind of water or wetpack then the plywood "Bone" then 3" of water or wetpack then the boards again then a few more inches of wetpack to simulate a broadside shot on a buff through the toughest bone.

For a tougher test set the board bones at a 22 and 45 degree angle from the flight path of the bullet to see how true it will go.

you only want a complete pass through on one buff so you dont get "Tagged" for a second one

Any thoughts on this buff medium test idea?

3" of water/wetpack then 1.5" of high grade plywood then 3' or water/wetpack and repeat the 1.5" of ply and 3" of water/wetpack.

Broadside buff simulator.

quote:

Originally posted by michael458:

quote:

Originally posted by boom stick:
Funny joke there Rip

I have a test medium thought

would not two 3/4" high grade plywood clamped or glued together simulate the toughest of buff bone?

If so then you can see the bullet path and depth of penetration by having a few inches of some kind of water or wetpack then the plywood "Bone" then 3" of water or wetpack then the boards again then a few more inches of wetpack to simulate a broadside shot on a buff through the toughest bone.

For a tougher test set the board bones at a 22 and 45 degree angle from the flight path of the bullet to see how true it will go.

you only want a complete pass through on one buff so you dont get "Tagged" for a second one

Any thoughts on this buff medium test idea?

3" of water/wetpack then 1.5" of high grade plywood then 3' or water/wetpack and repeat the 1.5" of ply and 3" of water/wetpack.

Broadside buff simulator.

Boomy

I'd rather make dinosaur mix!!!!!
M

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The 9,3 has a flatter front.
This is why testing at the same velocity twist and SD is needed.
Compare a true flat nose of the same weight to this blunt nose at the same velocity out of the same gun.

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The resistance of a rotating body to a change in its plane of rotation. The faster a body spins (the greater its angular velocity), the greater the stability of the body in its particular position or orientation. Gyroscopic stability accounts for the stability of a spinning discus or a spinning football in American football.

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The teacher of a sex education class wants the children of the class to give an example of sex in the animal world.
Little Lori raises her hand and says, "Well, my cat had kittens!"
"Very good, Lori!" said the teacher. "You know something about sex!"
Then it was Ricky's turn. "My dog had puppies!"
And the teacher praised Ricky also.
Next it was Bad Little Johnny's turn.
He thought a while. And then his face brightened.
"Daniel Boone!" he exclaimed.
The teacher was puzzled, as the rest of the class.
"Johnny, that doesn't have to do with sex! Have you been paying attention?"
"Why, yeah!" he said. "He killed a bear!"
The teacher was becoming impatient.
"But that has nothing to do with sex, Johnny!"
"Yeah, it does!" said Johnny indignantly. "Taught that bear not to fuck with Daniel Boone!"

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Since rpms is given by the velocity divided by the twist rate, it's getting more and more obvious (to me, anyway) that twist plays a definite role in penetration.

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Originally posted by ALF:
Someoldguy and Boomstick:

Does bullet spin influence penetration?

Let us look at it logically, if it is at all possible around this audience

Using linear mechanics: ( which is wrong for this problem btw)

Bullet: .458 cal
Mass: 500 gr
Linear velocity: V = 2000 fps
Barrel rate of twist: 1:14
In 1 revolution a point on the surface of the bullet will cover a distance of
.458 X Pi = .458 X 3.14 = 1.43812 inches in rotation.

At the same time to bullet moves forward at a velocity of 2000 fps

As the twist rate is 1:14 we see that for every foot ( 12 inches ) of forward travel the point on the bullet rotates 1.23267429 inches.

At 2000 fps the bullet rotates at a rotational velocity of only 205.445 fps

So our 458 cal bullet is going forward at 2000 fps this gives us a kinetic energy value of 500 x (2000 x 2000) /450000 = 4444 foot pounds of energy.

The rotational energy of the same bullet when spun is:
(205 x205) x500 / 450000 = 46.69 foot pounds of energy
That means that the rotational energy of the bullet is only 1.05% that of the forward kinetic energy.

But this is strictly incorrect because we are applying linear mechanics to a rotating body.

The correct formula for Rotational energy of a spinning symmetrical body (bullet) is defined by the following formula:

MErot = (1/2)Iω^2

where:
I = Transeverse moment of inertia of the bullet = (1/2)mr>2

m = bullet mass

r = bullet radius

ω is the revolutions per unit time ( rpm’s or rps’s or radians per sec ).

For rps the formula is:

ω = v x 12 / twist ( eg 14 for a 1:14 barrel)

so for the 500 gr 458 bullet @2000 fps from a 1:14 barrel this value will be 1714 revs per sec or 102, 857 rpm

The moment of inertia of the .458 bullet is:
Cal = .458
Radius = .229 and converting grains to pounds is:

I = (1/2)(500/7000)(.229/12)>2
= .00005404 lbm-ft>2

Rotational energy is calculated as, and converting lbm to lbf,

KErot = (1/2)(0.00005404)(2000)^2 /32.17 = 3.357 lbf

The calculated value is only about 3.357 foot pounds of energy, that is only .755 % of the linear kinetic energy value

This is in keeping with the energy calcutations of a Nato 30 cal military bullet.

The 30 cal Nato 9.5 gram bullet has a transverse moment of intertia
Of 6.0 x 10>-8 Kg.m.2

At 830 m/sec linear velocity and a angular velocity of 17100 rad/sec

The kinetic energy of this bullet is 3272 joule

The rotational energy is only 9 joule

Sellier and Knuehbeuhl show that in the case of the 30 cal Nato bullet the rotational energy accounts for only 0.003 % total energy of a bullet !

By changing the spin of this 30 cal bullet from a 1:14 to a 1:12 or even 1:10 barrel is going to squat to the values.

A few joules perhaps here and there, in rotational energy is going to mean nothing in the big picture.

quote:

Does bullet spin influence penetration?



Sellier and Knuehbeuhl show that in the case of the 30 cal Nato bullet the rotational energy accounts for only 0.003 % total energy of a bullet ! By changing the spin of this 30 cal bullet from a 1:14 to a 1:12 or even 1:10 barrel is going to squat to the values.

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Thanks. Don't know how I missed that one!
I'll surely use it, here in Kentucky,

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the greater the stability of the body in its particular position or orientation. (bold text mine, of course.)

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Originally posted by boom stick:
100 grain fracturing aluminium hollow points.

Great minds think alike.... Seems these aluminium bullets were used in a 45-70 already and in the 458 socom.
Shoot these things 3000 to 4000 fps and it would be interesting.

The 45-70 just became a varmit CQC round!

Shoot them backwards for the biggest splash.

Maybe fill the cavity with lead for more oopmph.



http://lehighbullets.com/products.asp?cat=19

The bullet is being released for orders on 1/9/09, but stock will not be available until mid-January 2009. The intent of the 458-300 was to create a fast fracturing bullet for personal defense and CQB applications to maximize terminal effect while minimizing potential secondary penetration. Well, it almost works! The terminal performance is simply unbelievable. At 3,000fps the bullet is a water-jug-vaporizing son of a gun. The problem lies in the amount of flash generated from the fast powders used to achieve the velocity. I use 40.0gr of Alliant 2400 in a 45-70 lever gun to achieve slightly over 3,000fps which results in a muzzle flash over ten feet long. You just can not believe how fast they cover 100 yards and they have shown to be very accurate in the several guns they have been tested in. There is virtually no recoil and the above load is just a riot to shoot. The bullet is made from aluminum and to eliminate the potential for aluminum oxide formation, the bullets are coated with a dry film lube immediately after they are cleaned. Weight - 100 grains BC (actual) - I still need to measure this; however, I can state it still has a lot of steam left at 100 yards. Length - 1.100 Design velocity - 2,000-?????!!!!! Material - 7075-T6 aluminum Sold in a packages of 50 at $50/box. Shipping via USPS Priorty Mail to the 50 states is included in the price.

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Here's what I'm looking at:
Do we not think a bullet continues to spin inside the target? (I'm mainly asking here. I'm just assuming that it does, otherwise there might not be stability. And evidence for this continued spinning seems to be mounting.)

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Posted 08 February 2010 02:03 Hide Post
Bump

These need a ride in your test medium don't you think Michael?

Backwards AND forwards.

quote:
Originally posted by boom stick:
100 grain fracturing aluminium hollow points.

Great minds think alike.... Seems these aluminium bullets were used in a 45-70 already and in the 458 socom.
Shoot these things 3000 to 4000 fps and it would be interesting.

The 45-70 just became a varmit CQC round!

Shoot them backwards for the biggest splash.

Maybe fill the cavity with lead for more oopmph.

quote:

Originally posted by boom stick:
Bump

These need a ride in your test medium don't you think Michael?

Backwards AND forwards.

quote:

Originally posted by boom stick:
100 grain fracturing aluminium hollow points.

Great minds think alike.... Seems these aluminium bullets were used in a 45-70 already and in the 458 socom.
Shoot these things 3000 to 4000 fps and it would be interesting.

The 45-70 just became a varmit CQC round!

Shoot them backwards for the biggest splash.

Maybe fill the cavity with lead for more oopmph.



http://lehighbullets.com/products.asp?cat=19

.

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The other aspect that I do not understand is that a bullet can penetrate straight in target for say 60 inches , over coming that drag for that long a distance, and then become unstable and stop at 63 inches and then we atribute this alone and alone to a twist that it is too slow for a given bullet (for example 410 gr vs 380 gr GSC-FN bullet).

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Originally posted by RIP:
boomer,
The point is really not to match a buffalo body nor an elephant skull inch for inch, but rather to produce a consistent test medium in which the bullets will behave similarly to the way they do in game.
Buckets of water and sandwiches of plywood might be easier for Alf to certify the consistency, but the wetpack is more "tissue-like."
A modular system of wetpack buckets would be easier for Alf to certify as consistent.
Easier to pack, soak, and weigh as smaller units before assembly into a train.
That still assumes only one shot per bucket of wetpack.
Could create a jobs program with Obama-stash stimulus cash to do this research.
Letter Rip