I think you're right claymore504, I would not expect a .40 HP to preform properly after going threw a barrier of anything other than paper or light clothing. They were not designed to shoot threw barrier's, the .357 Sig's were.
I read an article on why State troopers carry .357 sig. It stated that the .357 Sig would go through a vehicle body and still disable a suspect unlike the .45 & .40. I'll see if I can find the article.