That is the only mechanism of injury that can be duplicated in the lab.
Now from what I understand when we are dealing with permanent stretch cavity in gel, it is not representative of flesh. Correct? The elasticity of flesh closes up the stretch cavity, and what really matters at that point is the cutting from the pedals.
That theory was developed over 100 years ago and is actually low velocity vs high velocity. Low velocity was defined as under 1000 fps.
This is pistol rounds, mind you. "Temporary cavity" and "hydrostatic shock" are basically a non factor at the pressure levels which pistols operate, even the vaunted .44 Mag. Rifle rounds however there is a very real shockwave and temporary cavity that can cause organs to rupture.