Test Media...Soaked Phone Books?

S

Southern Shooter

New member
I understand there are various test media used to check bullet performance. I was reading one "home grown" test on-line and he used, and I quote, "Phone books were fully soaked for 16 hours".
http://www.btfh.net/shoot/bullet-test-1.html
http://www.btfh.net/shoot/bullet-test-1-results.html

Question:
Are the results obtained using soaked phone books worth any kind of consideration when pondering possible bullets to use for self-defense, i.e. expansion and penetration?

Thanks
 
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The "trick" (if there is one ;)) to doing a good bullet test is to use a consistent test medium. Soaked phone books (or newspapers) can't offer consistency due to varying paper types (glossy v. matte) and construction -think "heavy-weight" (ads) v. "newprint" (pages) v. "cardstock" (covers) which leaves calibrated gelatin or water. Then there's the issue of an adequate "soak time" -somewhere between one day and a few months depending upon who you ask. :D

If cost/ease of use is an issue, water is your best bet- just use a Fackler box (a long box that holds several one gallon storage bags full of water) and you can see what your rounds are doing. There are bullet penetration models (found in MacPherson's "Bullet Penetration" or Schwartz's "Quantitative Ammunition Selection") that will allow you to calculate terminal penetration depth and permanent wound cavity mass if you need to do so.
 
sigcurious: said:
While I have a guess at what this nonsensical phrase means, what does it mean according to the book it came out of?
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No, thanks. :)

Both authors (MacPherson, Schwartz) do a fine job of defining the concept in their books- so I'd just as soon not waste my time. :cool:

If you'd like to pursue it further, I am sure that with very little trouble you can obtain both of, either of, or neither of their books as you'd like. ;)
 
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A cavity has no mass. So the phrase, permanent wound cavity mass, is nonsensical. Whatever concept it is trying to define may make sense, but the phrase they came up with to describe it does not.

Seems silly to pay for a book, just to find out what they meant by a poorly worded phrase.
 
In the early 80's we used soaked phone books to compare prospective .45 ACP duty loads. The operative word here is 'compare' because they offer a reasonably consistent means to compare different loads. We didn't kid ourselves that they were representative of any load's performance against flesh and bone.
 
sigcurious: said:
A cavity has no mass. So the phrase, permanent wound cavity mass, is nonsensical. Whatever concept it is trying to define may make sense, but the phrase they came up with to describe it does not.

Seems silly to pay for a book, just to find out what they meant by a poorly worded phrase.
Click to expand...

OK, great. If you've figured it all out and deemed it "nonsensical" in your inestimable wisdom, then there is no need to ask, is there? ;)

It's their copyrighted material and I have no desire to retype a sizeable piece of it here to save you a few bucks and/or to satisfy your curiosity.
 
A cavity has no mass. So the phrase "permanent
wound cavity mass" is nonsensical.
Click to expand...

Everyone take a deep breath, reverse the phrase, add a word,
and think nautical:

"Equivalent mass of the permanent wound cavity"
The battleship Missouri displaces 50,000 tons of water
The bullet permanently displaced a volume of ½ kg of gel.

Using the mass permanently displaced by bullet travel
allows calculation of the relative energy dumped into
the wound area.
 
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Originally Posted by mehavey:
The bullet permanently displaced a volume of ½ kg of gel
Click to expand...
500 g? That is one big bullet!
Click to expand...

Would you believe (insert Maxwell Smart intonation here)

Code: 
     "... the bullet's passage imparted enough energy through both forward 
     and rotational velocity which when combined with its own mass and 
     that of the ejected mass/velocity of secondary ballistic gelatin produces
     a permanent void --- which if said void were filled with replacement 
     gelatin, that replacement gelatin would have a mass of "X" kg.

     This sir, is wound cavity mass.**


**(with apologies to both Bugle Notes and its Definition of Leather.)
;)
 
They must be describing the effect of a very large/heavy rifle projectile. The vast majority of SD handgun rounds typically displace 20-60 grams of gelatin/soft tissue whereas the big bore hunting calibers usually displace 85-125 grams.
 
Experimental bullets fired into "wet pack" (phone books and catalogs):

Swage44_6_1.JPG




Experimental bullet fired into an Elk: ;)

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Actual performance will be a little different, and penetration will be very different.

The actual test media makes a big difference, too. Newspapers and phone books are relatively soft, compared to catalogs, magazines, and glossy-paged books. But... it still gives you a reasonable idea of what the bullet might do.

To get an idea of what condition my media was in for the mostly-magazines-and-catalogs "wet pack" test above, I used 'calibration' tests:
To "calibrate" my test media, I fired a .177" BB at 625 fps. It penetrated 1/8". At that velocity, standard ballistic gel penetration is just over 3".
A Remington .22 LR Golden Bullet from a 22" bbl penetrated only 5/8". That stuff was packed tight.
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Those "calibration" tests showed me that that particular batch of "wet pack" media was ridiculously tough, and penetration would be a fraction of real-world performance. In addition, the tougher pages of the catalogs and magazines will strip more lead from the bullet's core than something like newspaper or phone books. So, recovered weights will be lower. But, expansion is usually fairly close to what the bullets do in soft tissue.

There's one important thing, though: The media has to be contained and held together in some way. If it's allowed to blow apart or a stack of phone books is allowed to separate when the bullet impacts, the test is worthless.
 
Rule of thumb; any factory round in suficent caliber will give suficent penetration.

Wound cavity volume = size of hole
Wound cavity mass = how much meat used to be there.

Corectly figured should be the same thing and I believe that is what this says--

"In Quantitative Ammunition Selection, Charles Schwartz presents an accessible mathematical model that allows armed professionals and lawfully-armed citizens to evaluate the terminal ballistic preformance of self-defense ammunition using water as a valid ballistic test medium. Based upon a modified fluid dynamics equation that correlates highly (r=+0.94) to more than 700 points of manufacturer-and laboratory-test data, the quantitative model allows the armed professional to generate ballistic test results equivalent to those obtaines in calibrated 10 percent ordnance gelatin. Using data generated from water test, the quantitative model accurately predicts the permanent wound cavity volume and mass, terminal penetration depth, and exit velocity of handgun projectiles as these phenomena would occur in calibrated 10 percent ordnance gelatin and soft tissue."
 
This beautiful in its simplicity and entirely consistent with what I've observed on big stainless steel tables (and other less sterile places) over the years.

taz1 said:
Wound cavity volume = size of hole
Wound cavity mass = how much meat used to be there.
Click to expand...
The only thing I can add it it is-

Hole in right place = involuntary incapacitation.

Of course there aren't any computer models or algebra involved, so I doubt it'll catch on.
 
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