A guess a person could always run 38 Colt and blackpowder 45 Colt spec rounds through a gel test. The issue with "proof" of a round's effectiveness during a war is that all evidence is anecdotal.

My Dad (and millions of Soldiers/Marines) left the Army with a wildly inaccurate view of the .45 ACP. A good hit anywhere in the body would knock the enemy down, etc. I am sure he also "knew" the M1 carbine was a pop gun and only a lucky shot with one would drop the enemy. That was the anecdotal evidence the military presented. He also left with a very high regard for the Garand, but that is based on fact. The M1 is the greatest battle implement ever fielded.

Andy