This is not how I wanted to start this site off with posting a warning and call to action over Pres Obama considering using executive order to ban M855 ammunition but this is one of the many reason AAP was created.
This video by YouTube gun & gear reviewer NutNFancy is a good explanation and warning of what this potential ban will mean for gun owners. The concern is not just about M855 but the door it opens to other types of ammo bans in the future. The .223 /5.56 round is the smallest of rifle rounds, if the admin bans this one round you can expect others to follow and then a move on larger much more powerful types of ammo.