As everybody knows, Cooper was writing during that era when 9mm hollow point ammo had a poor performance record. Said another way, during that time, the implication was that 45 hardball out performed 9mm hardball. Also, then the .38 Special revolver predominated, and it's round was the other cartridge that Cooper was comparing to 45 hardball. Having shot feral dogs with 38's, and the various 9mm and 45 rounds, I concluded that none was a humane killer unless brain cavity head shots were made. I will always remember one statement Cooper made. He said that all the handgun calibers will kill but pointed out that the other guy might disarm you, cut your throat, beat hell out of you, or shoot you before he dies if shot with an ineffective round. I paraphrased.