Reply #51: You need to also learn some history about firearms

[Retired AF Dem]

The M-16 and it's 5.56 caliber was forced upon the military in the 60's. Any guess which party was in power? At this time there is a ongoing project to maybe replace the 5.56 to the 6.8 since it has better stopping power than the 5.56.
http://www.military.com/soldiertech/0,14632,Soldiertech_M468,,00.html

FYI the 223 in considered a varmint round by hunters. You know wood chucks and such. Most hunting experts agree that it takes the same ballistic power to reliably kill a deer or a human and in most states it is not legal to hunt deer with the 223.