A few years ago I did an extensive analysis of all the known “stopping power” indices with representative bullet/velocity combinations for every bullet diameter available from the major American manufacturers. Thinking I had a better mousetrap, I used an index of my own design, substituting cross-sectional surface area for diameter in the Taylor KO index. I also tried substituting velocity squared for velocity, as this will give an index that accounts for energy, as opposed to the Taylor index, which effectively uses momentum multiplied by diameter.

Although I did the analysis on paper and can’t find it right now, I remember the somewhat surprising result. Except for energy, all of the other indices ranked all of the available cartridges the same, with few and minor exceptions. If a cartridge was found to have more “stopping power” than another by one index, it was ahead of the other by all indices. The only exceptions were when the cartridges were very close together, and then sometimes they would interchange, depending on which index was used. That basically meant they were a tie anyway.

Because bullet diameter is not considered, it is possible for energy to rank cartridges inappropriately. For example, a Trapdoor Springfield 45-70 load pushing a 405-gr bullet 1700 fps (more than I’m comfortable with) makes about 2600 ft-lb energy. Several 25-caliber cartridges firing 117 gr bullets will exceed that. For bison or bear, I would pick the Springfield, as I’m sure would most of you.

Energy by itself is a poor indicator of killing effectiveness. Whenever a new, hot-rod cartridge is introduced the manufacturers and gun writers exclaim the vastly increased energy over the competitors. There’s one reason for this; if you increase velocity a little you increase energy a lot. It makes better advertising to claim an additional 100 ft-lb than 50 fps.