After months of crime-lab testing, the Dallas Police Department adopted a hollowpoint service load. The box lacks the +P designator because that standard did not exist in 1973.

Without imaging gear, we could not do a direct measurement of the first 15cm of a long gelatin block. Our solution was to cast blocks to size, making one dimension exactly 15cm. We managed to acquire a professional kitchen mixer for the gelatin, and we were on our way.

Direct determination of energy transfer meant measuring the bullet velocity as it entered the block and as it exited. We had but one chronograph then; thus, simultaneous entrance and exit velocities were not possible. So the first series of tests involved shooting 10 rounds for velocity at 15 feet and calculating the average kinetic energy. We then placed a gelatin block at 15 feet with the chronograph screens behind to read exit velocity, and we fired again. Averaging 10 exit shots, figuring the retained energy, and simple subtraction should provide an energy transfer number.

To see if this cobbled-up rig would work, we had to test AFIP’s only two handgun data points: the 9mm Luger and the .45 ACP. Based on AFIP’s photo-interpretation system, the transfer numbers were around 110 ft-lbs for the 9mm Luger FMJ and 120 ft-lbs for the .45 ACP FMJ. Our first firing tests showed that our low-tech rig gave energy transfer numbers within 2 to 3 percent of the very pricey AFIP setup. We had the test system we needed.

The Tests
The Winchester salesman left the captain some samples of the then-new .38 Special ammo, a 158-grain lead semiwadcutter (SWC) at standard velocity. The most basic need of the test was to compare the wound cavity volume of the proposed SWC round to that of LRN ammo. We had plenty of gelatin, time set aside for testing, and a keen desire to see what this new test could reveal. After all, the ammo industry was just beginning to react to the Super Vel hollowpoints by Lee Juuras. We bought-- and scrounged--enough to have 15 ammo types representing various bullets and velocity levels. It’s a good thing we did; the final recommendation was not the load the salesman proposed to the captain. A selection of the tested .38 Special loads is listed in the accompanying chart ranked by relative wound cavity volume.

We selected an S&W Model 15 revolver with a 4-inch barrel as the test platform and started with several brands of standard-velocity 158-grain LRN ammo. All produced similar wounding abilities of roughly 75 ft-lbs transferred to the blocks. The testing was entirely comparative, so the consistent performance level of LRN ammo became the baseline to which other ammo types would be judged. According to the AFIP criteria, ammo transferring 150 ft-lbs produced a temporary cavity twice that of the .38 LRN producing 75 ft-lbs.

Next we tested the Winchester load the salesman had left plus other SWC loads at both standard and high velocities. At standard velocity, the SWC posted a small but statistically insignificant advantage over the LRN loads. At what today would be .38 Special +P velocities--the +P indicator was not standardized until 1974--the SWC showed a modest advantage, posting transfers of around 95 to 135 ft-lbs depending on make and velocity. For giggles, we shot some 148-grain hollow-base wadcutter ammo; it consistently hovered at 145 ft-lbs transfer.

We couldn’t resist shooting one of the old police favorites, the 200-grain lead RN. One brand transferred less than 60 ft-lbs. Another managed to transfer 85 ft-lbs because its odd nose profile caused it to tumble violently almost as soon as it entered the gelatin.