This is remarkable work! It is the best of its kind I have seen. For defense rounds, this has some really worthwhile information presented in a form that meaningfully compares the different bullet types and calibers. I was looking for more info on the 44 mag because that's one of my favorite cartridges, but then it dawned on me that you are studying defense cartridges.
One observation is that some very different bullets from different cartridges will penetrate to about the same depth, but some are known to be more deadly than others. I don't know if this is a function of velocity, diameter, or both.
Fascinating! I'm going to have to poke around on your web site a lot more than I have been.
It is a combination of what you have mentioned, but most importantly, it is a matter of the construction of the bullet.
They softness of the lead, the type of jacket material (where a jacket is involved) and any special little "goodies" different manufacturers hype on (Gold Dot, JHC vs. JHP, Hydra-Shok and Hydro-Shok, XTP, etc.).
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