I think the tests are interesting but I don't take them real seriously because of the lack of calibration, density, etc. They're a step above wetpacks and gallon jugs of water.
If I were going to do anything approaching serious terminal ballistic testing, I would use a chronograph and invest in Sim-Test ballistic gel
. It's reusable and would be a lot easier on the pocketbook than the standard gelatin used by the FBI, etc.