Understand, I have nothing against any of the calibers mentioned. In fact, I own numerous examples in each caliber and regularly stake my life on them. Having said that, the US military went to the 9mm as the quid pro quo of NATO adopting 5.56x45mm. The Feds have gone back to 9mm for several reasons, including cost of ammo, less wear & tear on pistols and it's easier for all the agents to qual with. Most of law-enforcement will eventually follow them back, for the same reasons, I'm sure. In the end, the old saw about "I'd rather be missed with a .500 Magnum than hit with a .22" still rules.US Military and Federal Law Enforcement have gone to 9MM. I went from 45 to 9mm in 1989. So I guess you know where I stand. But you do nee the right SD ammo if you do it.