From: gmk@falstaff.mae.cwru.edu (Geoff Kotzar)
Subject: Re: Wound Ballistics and 9mm Bullet Performance ( LONG )
Organization: Case Western Reserve University

In article <36661@mimsy.umd.edu> joel@peora.sdc.ccur.com (Joel Upchurch) writes:

#The problem with using ammo that will get sufficent penetration,
#even in the worse possible case, is that it is going to over
#penetrate in most other cases. One woman has already been killed
#in LA when a 147 grain 9mm bullet went through the suspect and
#killed her. Massad Ayoob talked about this issue in his Cop Talk
#column in the July/August American Handgunner. One interesting
#aspect of his column is that he also quote Dr. Fackler as an
#authority and reaches the opposite conclusion concerning the
#desirability of of the 147 grain bullet.

With all do respect to all of the above named individuals, it would appear
at least to a poor ignorant individual like myself, that overpenetration is
the biggest red herring in the handgun stopping power debate. Remember that
fully 75% -SEVENTY-FIVE PERCENT, 3 out of every 4- of the rounds fired in self
defense miss their target totally and go screaming out into the ranks of
innocent bystanders without attenuation. At least without the attenuating 
effects of having passed through a living body. How much energy is given up
in the process is problematical and debatable: a little, some, most? The
important point is that the other 75% of the fired rounds are potentially
more dangerous having not impacted an assailant.

For those not familar with the Ayoob article he cited three cases of of over-
penetration:

1) 1989, Philadelphia cop is killed by .38 slugs from police passing through
   a felony suspect;
2) 1990, Univ. of Arizona campus, officer A fires at suspect and bullet passes
   through suspect's ARM and goes on to kill officer B;
3) 1990, So. Cal., L.A. sheriffs "became embroiled in a shootout with an armed
   robber". Badguy ran into the doorway of a mom 'n pop convenience store. Mom
   was behind the badguy when police fired, bullet passed through the badguy,
   mom died, badguy lived.

The questions which should be asked are 2) how many makes of ammunition now
available would not have passed through a human arm with an average thickness
of maybe three inches, and 3) how many rounds were fired by the officers
"embroiled in a shootout with an armed robber" and how many of the rounds that
totally missed the robber went on to hurt a bystander.

In #2 above Ayoob is begging his data which alone may indicate that overpene-
tration is not be the problem he makes out. A human arm does not offer the
resistance of a solid torso hit. Practically every cartridge made today with
the notable exception of the Glaser can completely penetrate an arm, at least
transversely. Even a Glaser will exit on many of the shots. Even if Ayoob
stated that he preferred a load that would only penetrate 6 inches in gelatin,
half of that recommended by Fackler, it still would completely penetrate a
human arm. As Ayoob presented the data it does not qualify as an "overpene-
tration problem"; I would almost classify it as a miss.

Case #3 above indicates the second form of data misrepresentation in this
issue. Which is a greater threat: missing or overpenetrating? You and I
do not have the data but these experts do and they either are sitting on it
or they have not really examined the problem. For instance how many rounds
that impact an assailant/suspect go on to overpenetrate. We already know
from the FBI data what precentage of rounds fired at an assailant/suspect
actually hit. For example if 10% of the shots that hit the intended target
overpenetrate then we are looking at only 2.5% of the total number of rounds
fired. This number then has to be compared with the 75% that miss. The number
of shots that miss are 30 times more likely to injure an innocent bystander
than those that overpenetrate. Secondly, how many of the misses actually
result in injury to innocents. In Ayoob's report on the FBI Miami fight with
Platt and Matix he noted that something around 150 rounds were fired resulting
about 25-30% hits. That left 120 rounds to be stopped by what or whom? He did
not report that any of the civilians in the neighborhood were injured.

I suspect that it is much easier and cheaper as a city father to reduce your
liability by claiming to have incorporated the findings of the latest "scien-
tific" study in your choice of ammunition which does not put your constituents
at risk from overpenetration from police shootings than to actually reduce
their risk by demanding superior training and performance from your officers.
By deflecting public attention from the real problem of officer performance to
the sacrificial one of hardware improvement they are able to appear as caring
and conscientious and all at an affordable price.

This posturing on the part of experts and politicians does not change the
realities of a gun fight. Bullets must hit their target and penetrate deeply 
enough to injure the vitals to effect a stop reliably. The one shot that
connects and penetrates through is less of a hazard than the three preceeding
shots that miss. Until the people with access to the data present a complete
picture based on all the data rather than selecting examples to advance their
own prejudices, you and I will have to scrutinize the little factual infor-
mation we are given and draw conclusions based on our own common sense.

Geoff Kotzar


From: gmk@falstaff.mae.cwru.edu (Geoff Kotzar)
Subject: Re: Home defense weapon (WAS: 9mm Glock 17)
Organization: Case Western Reserve University

In article <36997@mimsy.umd.edu> crs@beta.gov (Charlie Sorsby) writes:
#
#In article <36902@mimsy.umd.edu> ke4zv!gary@gatech.edu (Gary Coffman) writes:
##
##becoming the favorites with police. Many many gunbattles are taking
##place in housing projects where children or other innocents may be
##only a partition away yet out of sight of the officer. This is why
##there is concern about overpenetration and heavy bullets in general.
#
#I guess that I'd be surprised if *any* bullet capable of
#penetrating even half the thickness of a human body couldn't also
#penetrate two thickesses of dry-wall.


(some stuff has been deleted)



##use light hollow point ammo because the city council and the public
##have been educated to the dangers of over penetration by a series of
##tragic through the wall shootings.
#
#Your point isn't obvious to me.  Are you saying that those
#hollowpoints won't penetrate two layers of sheet-rock and still be
#dangerous or are you saying that they won't penetrate a human body
#*and* two layers of sheet-rock?
#
#Those are two very different things.  Unless we are very clear
#about which of the two is under discussion, we are very likely to
#be carrying on two different conversations together.  
#
#Best,
#
#Charlie "Older than dirt" Sorsby				"I'm the NRA!"
#	  crs@lanl.gov


You are right that there is a difference between these two characteristics
of bullet performance. "Overpenetration" refers to a projectile producing
a through and through perforation of an animate target. "Tactical Penetra-
tion" refers to the ability of a projectile to pass through intervening
obstacles and still be able to inflict a wound, serious or otherwise. Such
obstacles include auto bodies, heavy clothing, and house structures. You
get both soft tissue penetration and tactical penetration to differing 
degrees with different loads and you in fact want a certain amount of each.

No matter how much you might say you would never engage an assailant
through a car door or window, or would shoot someone in your house through
a wall, there are occasions where you may need that capability.

I must confess to being confused about how the combination of bullet weight
and velocity combine to produce soft tissue versus tactical penetration.
The early light weight .38 SPC work seemed to indicate that light bullets
and high velocities produced greater tactical penetration and reduced soft
tissue penetration than heavier slower bullets. In the same caliber and
cartridge of course. But when I started looking across different cartridges
and wildly differing velocities, weights, and constructions my intuitions
started running amuck. Maybe someone out there has a reference to a system-
atic study of soft tissue and hard target penetration as a function of
bullet weights, velocities, and constructions. I would appreciate hearing
about it.

Geoff Kotzar
 

From: gmk@falstaff.mae.cwru.edu (Geoff Kotzar)
Subject: Police Hit Ratio
Organization: Case Western Reserve University

In a previous posting I mentioned that police manage to connect with
their intended target about 25% of the time. I cannot trace this back
to a national survey like the FBI Uniform Crime Reports or the like. I
am still trying to find the source document. I can, however, cite one
of a number of articles where this number has been quoted.

The following quote is from American Handgunner March/April 1990,
"The Ayoob Files", page 110-111.

"Their 33% hit potential at a distance nearly twice that of the farthest
moving target at the difficult Bianchi Cup compares superbly to a national
average of 25% hits with double action revolvers in police gunfights at
much closer ranges."

I do not know how this 25% hit rate compares with the current average
now that high capacity 9mm's have come into more widespread distribution,
but with their invitation to hose down an area I would not be surprised to 
find the number even lower. You must however remember that they are performing
under very high stress and I don't know how well I would do under the same
circumstances. I therefore do not want to be overly critical without more
info about the quality of their training, but 3 out of 4 bullets missing
their intended target still pose more of a problem to civilians than bullets
that overpenetrate.

Geoff Kotzar