I found something interesteing while doing research on the 1928 Thompson Submachine Gun. Click on link below, look in column on right. Click on General Thompson, and read the 3rd paragraph from the bottom of the page. I've also qouted it below.the link.
In 1904 Thompson and Col. Louis A. LaGarde conducted tests to find the caliber most suited for military handgun ammunition. The tests included firing shots into live cattle at a Chicago slaughterhouse, and into human cadavers obtained from medical schools. The conclusion? Large and slow moving bullets of about .45 caliber were much more destructive than smaller bullets moving at high velocity. With this knowledge in hand, Thompson was instrumental in developing the .45 caliber rimless cartridge, later adopted for use in the Colt Model 1911 pistol designed by John Browning. Eventually this same cartridge would be chambered in Thompson's Submachine gun.