SB>VH>There is no "formula" that will predict bullet
performance -- kenetic
SB>VH>energy, while scientifically sound (derived by Newton, from his laws of
SB>VH>motion) doesn't tell us how the bullet will perform.

SB>VH>As an example, a .223 (5.56X45 NATO) round has more kenetic energy than
SB>VH>a heavy .45 Colt load.  Yet the .45 Colt would be a more reliable
SB>VH>"stopper" in a fight.

SB>So, is it a matter of where (how deep and over what cross-sectional
SB>area) the energy is delivered? Aren't NATO bullets clad specifically
SB>to minimize expansion, so tend to overpenetrate?

As I said, there is no formula -- when it comes to prediction, "stopping
power" is as ellusive as weather.

Military bullets under the Hague Convention, must not be designed to
cause "unnecessary suffering."  This has been interpreted by legal minds
-- who know nothing about ballistics -- to exclude certain types of
bullets, and virtually require other types.  For example, in Viet Nam,
our tunnel rats carried .22 pistols.  Normally, the .22 pistol has a
lead bullet.  We had to develop jacketed (or full metal patch) bullets
for these guns.  Which is nonsense -- jacketed or not, a .22 Long
Rifle is a .22 Long Rifle.  There is no discernable difference in
terminal ballistics between jacketed and unjacketed bullets.

"Overpenetration" is not a military concept -- when you shoot at people,
they tend to get behind things.  Most men who are shot in combat are hit
by bullets that passed through something else first (walls, logs,
sandbags, earth, vehicles, and so on.)  It is therefore a distinct
advantage to have a military cartridge that will penetrate material
barriers.

That being said, there are two effects of military bullets that can
increase lethality -- one is the bullet breaking up.  Full metal jacket
bullets tend to become unstable when transiting media (from air to the
more-or-less liquid environment of the body.)  Normally, they will yaw,
reaching a 90-degree yaw in about 12 to 18 inches of travel, and
reaching 180 degrees in about double that.  After that, they tend to
re-stabilize and travel base forward.  Some bullets will exhibit a
double lobed yaw -- that is, they will yaw 720 degrees before stopping.

Usually, this is academic, since most of the yaw occurs after so much
penetration that a human body would have been fully penetrated.
However, in some cases, the yaw causes stresses on the bullet, which
breaks apart along the cannelure (the knurled "belt" where the case
mouth is crimped.)  This results in secondary missiles which move at an
angle to the original trajectory, and which can increase lethality.

The second effect is seen in the Russian 5.45X39 cartridge.  This bullet
has a short core, which occupies the back portion of the jacket.  The
forward portion of the jacket is filled with air (it is not a "hollow
point" since it has no opening to the outside.)

The Russians claim this construction produces greater accuracy -- it
puts the center of gravity behind the aerodynamic center.  And that is
true.

But on impact, the jacket tends to decelerate, while the core moves
forward, so that the center of gravity is suddenly ahead of the
hydrodynamic center.  This dramatically unstabilizes the bullet, which
yaws immediately and continues to yaw.  Normally, the bullet will exit
sideways in something as small as a thigh muscle, leaving a very serious
wound.
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