[320pf]

You are correct about the average straight on chest thickness. However, I would ask to to stand in front of a mirror and mock-up like you are shooting a rifle at your image. What would be the entry angle to the target? Most likely not straight on but more side-to-side and quartering. The average chest width is about 14-17 inches without considering the thickness of an arm. An arm would add about another 4-5 inches. Hence why I think that the penetration is about right.

Now for four legged critters the average chest thickness is 8-18 inches... Now think of a quartering shot which would add more apparent thickness.

Here is a summary of the gel data.
The Speer TNT
Figure 10&11 max cavitation depth 3.1"-13.6"
Figure 13&14 2029fps max cavitation depth 7.1" – 18.5"
Figure 16&17 2190fps max cavitation depth (7.1 – 18.5 typo??) ~3.1-~12.6 measured from the figure.

Nos125
Figure 19&20 2011fps max cavitation depth 2.7 – 14.8
Figure 22&23 2026fps max cavitation depth 4.3 – 18.1
Figure 22&23 2152fps max cavitation depth 0.8 – 18.1

320pf