If you did some searching you would have educated yourself on the true reason for the 40. It was another failed attempt at finding a caliber to replace both the 9 and 45. Proper traing with the standard of the time would have led to a better outcome, however it was easier to blame the weapon caliber.
There are zero hand gun Calibers out there that will end a confrontation quickly, unless a brain or spinal shot hits home. IMHO the 9 is the superior cartridge due to its multiple shot controllability for both an inexperienced and professional operator. The 45 is another fine round that requires some work to double tap. The 40, well is a wannabe caliber that can be a handful for any shooter.