The medical findings were eye-poppers. In the initial flurry of .357 Mag. bullets, one fired parallel to the plane of the shoulders struck the suspect in the left armpit and traveled across the left lung and lodged lightly in the heart muscle. The officer had purchased a 110-grain JHP load with very fragile bullet construction; the jacket appeared to have been designed for .38 Spl. velocities. The wound-cavity volume the load produced in gelatin was about 51⁄2 times that of the baseline .38 Spl. and very high among wound volume producers, yet it failed to stop a dangerous man.

BASELINE WOUND VOLUMES
CARTRIDGE	BARREL LENGTH (in.)	BULLET WEIGHT (grs.)	BULLET STYLE	BASELINE WOUND VOLUME* (ft.-lbs.)	WOUND VOLUME RANGE (Newer Loads)
.25 ACP	2	50	FMJ RN	51	(not tested)
.380 ACP	3.25	95	FMJ RN	74	133 to 170
.38 Special	2	158	Lead RN	62	137 to 214
.38 Special	4	158	Lead RN	77	136 to 392
9 mm Luger	4	115	FMJ RN	107	176 to 377
.38 Super	5	130	FMJ RN	138	376 to 393
.357 Magnum	4	158	Lead SWC	166	212 to 502
.41 Magnum	4	210	Lead SWC	188	498 to 618
.44 Special	4	246	Lead RN	69	194
.44 Magnum	4	240	Lead SWC	636	538 to 639
.45 ACP	5	230	FMJ RN	114	170 to 353
.45 Colt	4	250	Lead RN	159	165 to 386
* Temporary cavity is expressed as ft-lbs of energy transferred to ordnance gelatin. Newer loads were tested from 1974 to 1986.

The suspect was part of the problem. In addition to being heavily muscled, he carried a load of fat around his upper chest and armpit areas. The fragile bullet had to traverse much more tissue than in a face-on shot to an average person. It also shed nearly half its weight, reducing the energy carried to the vital organs. The wound evidence indicated that the bullet velocity was very low as it penetrated the left lung. In the 30 to 45 seconds between taking a fatal hit and actually going to ground, he could have done a lot of damage with his little .25 ACP.

Revising The Standards
We needed to find out what was missing from the picture. Officer-involved shootings gave excellent data. We had the gun and ammo evidence in hand, and we usually interviewed the officers. We could get very accurate descriptions of the wound tracks from medical examiners and trauma surgeons. And then there were the gelatin blocks.

Being rather amazed at the diverse shapes of wound tracks in the nearly transparent gelatin, we had sketched many. Like tissue, gelatin springs back to original size after being shot, but its transparency reveals shear lines that closely define the position of the temporary cavity. Not immediately seeing a numerical way to evaluate cavity position, we started comparing street results with the cavity shapes produced by the ammo types. The cloud began to lift.

Ammunition with numerically large wound cavities yet posting poor street results often featured lightweight or lightly constructed bullets at high velocity. This included many .357 Mag. and 9mm Luger loads. Their cavities tended to reach maximum diameter in the first 2 inches of the 51⁄2-inch gelatin block. The remainder of the cavity was basically bullet diameter, and some loads failed to completely pass through the block.

Reviewing cartridges that produced good street results showed the cavity shapes were much different. These produced cavities that were distinctly shaped like a football, with maximum diameters positioned around 3 to 4 inches into the blocks. We had fallen upon a key factor. Although wound-cavity volume as determined by military methods was important, the distribution of that cavity was equally if not more important. We had numerous shooting results where a cartridge producing a modest cavity volume of proper distribution—like the .38 Spl. lead HP load we recommended—was more effective in the real world than cartridges making a much larger cavity that was too shallow.