I just saw a link to an extensive test the other day that involved .38 special and .357 Magnums in at least 30 different flavors shot from 2" and 4" revolvers. The bad news, only a few of the .38 Special loads expanded. I believe the Hornady Critical defense was one and the Winchester PDX1 was another, I forget the third. The .357 magnums pretty much all showed incredible expansion.