It seems that one of the perennial topics on internet gun forums is the comparison of the 9mm and .45ACP using ball ammunition.
Using the Schwartz terminal ballistic model to analyze the maximum penetration depths and the corresponding mass within the permanent wound cavities of the 9mm 115 gr FMJRN and the .45ACP 230 gr FMJRN across a wide range of velocities (200 fps - 1600 fps), I thought that graphs might be a visually-informative way to illustrate the data for those who might be interested in it.
Since a bullet that lacks the velocity necessary to penetrate skin will fail to penetrate a human body, it was necessary to determine the lower velocity limit to be used in the analysis.
For this task, I used the skin penetration model found in the research paper below-
-to determine the minimum velocity at which both the 9mm and .45ACP FMJRNs would successfully penetrate human skin of average thickness (~3mm). Those values are 194.5 fps for the 9mm 115 gr FMJRN and 179.4 fps for the .45ACP FMJRN.
Since either round must have a minimum velocity of less than 200 fps to pass successfully through human skin, 200 fps was used for both rounds as the lower limit for the analysis.
This graph illustrates the maximum penetration depths (in inches) of the 9mm 115 gr FMJRN and the .45ACP FMJRN at impact velocities of 200 fps to 1600 fps-
This graph illustrates the mass (in grams) of permanently crushed soft tissue within the entire volume of the permanent cavity of the 9mm 115 gr FMJRN and the .45ACP FMJRN at impact velocities of 200 fps to 1600 fps-
Using a manufacturer's ballistic table to determine the velocity of the FMJRN at a desired range, the maximum terminal penetration and the amount of permanently crushed soft-tissue within the permanent cavity can be found using the charts above.
One of the most startling implications of this analysis (at least to me) is the amount of penetration that both rounds would produce even at extended ranges where velocities are well below 400 fps.