There's a reason now the Army is training the "controlled pairs" technique when utilizing the M16/M4 family of weapons. Lord knows I have personally witnessed the ineffectiveness of 5.56mm to the center mass of individuals. You pump agressors full of drugs or in our case, adrenaline, you have your hands full at that moment. The Army has realized the lack of stopping power, yet continues to stick with the NATO cartridge. Granted the USMC and their infinate wisdom are recieving a newer 5.56mm (MK318 Mod 0)cartridge designed for rapid fragmentation and holding together through barriers. Bumping it up to a 62 grain round is a start, but I won't say a solution.
Greg/Others here's the scoop:
http://www.marinecorpstimes.com/news/2010/02/marine_SOST_ammo_021510w/
Given a choice, I personally rely more on my 7.62mm crew serve over my rifle for the simple stopping power differences. I hold the same principles with my own defense. Where some believe 9mm is adequate, I don't feel comfortable. I won't doubt I will hear shot placement blah blah blah, but if you have ever been in situations, good luck in getting a head shot off Chuck Norris, IT DON'T HAPPEN.
PS- We have established Josh will never grab his .22's to shoot an agressor.