Yes and no. It gives a pretty good idea of how one round compares to another round as it is a standardized medium. But as far as a human body, no. The human body is not 12 inches of the same consistency. You have skin, fat, muscle, bone, organs, air spaces, fluid filled spaces, etc. Each have a different effect on the bullet. A shot to the abdomen on a person who is very fat may not even get thru the fat layer. On the other hand a shot to the chest can blow right thru because the chest is full of air. There is one gun expert (Massad Ayood) who went thru tens of thousand of records to see what round had the best one shot stop. It was the 125 grain 357 magnum semi-jacketed hollow point. However the most important factor is bullet placement. Unfortunately due to the large magazines in most semi-autos these days, people do not focus on that and just fire as many rounds at the target as possible and hope they get lucky. As a result people will be shot multiple times before they go down and along with that, there are multiple misses that endanger others.