re: Soldiers Hate the M4 and M16. The Pentagon Is Finally Doing Something about It.

Supposedly the .223 round was used so that the enemy would have to spend more time picking up wounded from the battlefield. There was also another benefit: the M-16 and the .223 round were lighter than competing platforms like the AK-47. If you've ever held an M-16 with a full mag of ammo and then held an AK-47 with a full mag of ammo, there is a significant difference in weight. This is a big deal to the grunt having to lug around a rifle in the middle of a 95 degree jungle.