FMJ Overpenetration: Truth or Myth?

Regards the Ayoob article, when NYC went to the 9mm, one of the statistics that also rose was the total number of shots fired by officers w/ autos, as to those fired back in the revolver days.
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well,..duh...:D

Stands to reason, doesn't it??

In the revolver days, the most a pair of cops could hose off when they had to light someone up was 12, before needing to reload. Today that number is 30+!!

And, most of those shots do NOT hit the intended target!!! Yet, every bullet goes somewhere...

This has always been a problem, but today, when officers can fire nearly 3X the number of rounds, before reloading, the odds of one or more of those rounds having unintended consequences is hugely increased.

I was most impressed with the shoot out that happened not all that long ago, where the bad guy shot a couple rounds at the cops, hit nobody, and the cops shot a lot of rounds back, missed the bad guy, and hit half a dozen or so bystanders, KILLING a couple of them!!!

TO me, this clearly illustrates that while the danger to bystanders from overpenetration is a real risk, it pales in comparison to the risk from cops shooting and MISSING the intended target.

And, with 2-3 times the bullets to miss with, (semis compared to revolvers) then yes, even if the rate of misses stays the same, the numbers are going to go up.
 
SonOfScubaDiver said:
So, I'd like to get your opinion on over penetration with FMJ. Is the risk real, or is it just a myth concocted by bullet manufacturers to get us to buy more expensive hollow point ammunition?
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The risk is real. Just look at the annual SOP9 reports filed by NYPD back in the early 1990s when they were issing the 9mm 115-grain FMJ to their officers in the name of offering a more 'humane' ammunition choice. Several folks were struck and killed by 9mm 115-grain FMJs that passed through a suspect during NYPD OISs. Both the 9mm 115-grain FMJ and the .45ACP 230-grain FMJ penetrate deeply in gelatin tests. The 9mm 115-grain FMJ will penetrate to a depth of 27 - 29 inches and the .45ACP 230-grain FMJ will nearly duplicate that with 26 - 28 inches of penetration in gelatin.
 
ShootistPRS said:
Dr. Fackler used ballistic gel at a precise ratio and at a precise temperature. He even found a way, using a BB to "calibrate" gelatin. He also used what is called a "Fackler Box" that uses water and freezer bags in a long apparatus that could correlate penetration compared to ballistic gelatin. The Fackler box is a great way for the common man to test bullets for both expansion and penetration. If I remember correctly (possible) it was necessary to multiply the penetration in water by .557 to get the amount of penetration in gel. It is a very accurate way to get repeatable results when testing bullets for terminal ballistics. I built two (the first one blew apart on the first shot) and tested both pistol and rifle bullets. The box is not really very portable and you have to have enough water to fill new bags each time but you get repeatable results every time.
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Got a question for you; hopefully you can help and apologies for the topic drift. I have seen the water-to-gelatin conversion factor that you quoted, .557, more commonly expressed as 1.8x, frequently. Do you have, or have you seen any documentation in which that particular conversion factor is listed? The reason that I ask is that have been chasing that particular demon down for years with no success.
 
I can tell you that it was listed in one of the papers that Dr. Fackler wrote but It has been so long ago that I could not produce it. The 1.8 is the inverse of .557 rounded up so it has to be close.
If a bullet penetrates 1 foot in gelatin then it will penetrate 1.8 feet in water. And the inverse is if the bullet penetrates 1.8 feet in water it will penetrate 1 foot in gelatin. 1.8 x .557 is 1.0026 (the actual conversion number is 1.79856 and not 1.8 but it is close enough.)
 
Ah, thanks. This confirms that my collection of papers by Fackler may not be as complete as I'd like to think it is. :o
 
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