From:	Adam Getchell acgetchell@*******.edu
Subject:	Armor Penetration
Date:	Fri, 26 Feb 1999 10:36:29 -0800

When considering the damage potential of a weapon, there are three main
criteria:

Kinetic energy, as it relates to the amount of joules the weapon can
deliver to the target. This relates directly to tissue damage.

Momentum, which provides knockdown capability but, more importantly,
preserves kinetic energy through the trajectory of the round.

And physical characteristics of the bullet; ie diameter, elasticity,
aerodynamics (both in-flight and within the target). This affects both
energy retention in flight and energy delivery to the target in terms of
wound channel and tissue damage.

Dr. Martin Fackler of the Wound Ballistics Lab in Maryland has published
that "damage" is primarily a function of kinetic energy. Also, "hydrostatic
shock" does not add significantly to trauma caused by round impact, with
the sole exception of rigidly contained areas of the body (ie the skull).

Finally, as far as the question of barrel length, note that there is an
optimal length for each round wherein the gunpowder deflagration imparts
maximum energy. Shorter barrels lose some of this energy transfer, while
longer barrels reduce the total energy with friction. An edition of Guns
and Ammo ran several tests with various length barrels and a ballistics
setup to demonstrate this point.

As such, Shadowrun miserably fails to tie in these factors in any sort of
meaningful way. For example, let's put the standard rifle in the .303 class
of weapon. There are two damage levels, 7S and 10S, which we'll assume
relate to barrel length (carbine and rifle respectively).

Now lets take the Barret sniper rifle, .50 caliber weapon, 14D. We may
attest that the increase is due to higher velocity, heavier round, and a
longer barrel. However (and I don't have any ballistics tables on me), I'm
not sure that the velocity difference between a .303 and .50 is large (by
which I mean it is within a factor of 2), but we'll leave that open.

Now let's compare a Heavy Machine gun, which by rights would be a .50
caliber /14.2mm weapon also, and does 10S.

Compared with a Barrett, an M2 .50 HMG lacks only barrel length and
possibly, improved bullet composition. As I noted above, though, barrel
length factors are at most 10-20% of kinetic energy. The jump from 10S to
14D is puzzling in that light, unless we postulate the existance of
ammunition that is able to increase power by +4 and wound level by 1.

Perhaps that is how one could model the .224 BOZ pistol round, which is
capable of penetrating armor panels in the Bradley AFV and the next
generation of body armor, but I would not like to see such escalation.

When I proposed the OICW Block 4, I was extremely conservative in the
effects of ETC propellant. Imagine an assault rifle firing rounds at 2000
meters per second or so. Using the examples that have been given to us in
FOF and elsewhere, how would one model a doubling of kinetic energy?

Perhaps someone with access to ballistics tables will add comments?
--Adam

acgetchell@*******.edu
"Invincibility is in oneself, vulnerability in the opponent." --Sun Tzu