Article is about MARSOC given the green light to use the G19...but it is this section I am focusing on:
Many American combat veterans disagreed with the switch to a 9mm pistol, but that advice was ignored.
But times have changed.
Since 2001 American troops in Iraq and Afghanistan discovered, through combat experience, what types of weapons worked best at close range to take down the enemy. It was the same with SWAT teams and commandos all over the world. When conducting a raid and finding yourself up close and personal with someone trying to kill you, there is a need for a heavy caliber pistol or a shotgun (firing 00 shot or slugs).
The premier pistol for ensuring you take down someone is still the .45 caliber (11.4mm) or .40 caliber (10mm, but only with a heavy bullet) pistols. There is also a .50 caliber (12.7mm) pistol, but only very large people can handle this one. The 11.4 and 10mm pistols are light and handy, compared to assault rifles or shotguns, and have a long history of quickly taking down an armed and determined foe.
SOCOM (Special Operations Command) came into being a few years after the M9 was adopted and immediately began planning to bring back .45 pistols for its commandos. Actually,
many Special Forces and SEAL operators never gave up using the .45, as it was the ideal pistol for many commando operations. SOCOM had its own budget and was allowed to adopt a number of 11.4mm pistols for its personnel.
http://www.strategypage.com/htmw/htweap/articles/20150305.aspxI will always rate professional field experience and professional preference over pointy-headed clinical tests, statistical machinations and subjective psudeo-objective findings thank you very much!