chief-the-army-has-developed-a-bullet-that-penetrates-556-mm-resistant-body-armor

This is not a great revelation. It was common knowledge that Iraqi insurgents and the Taliban used 7.62 mm AP rounds to attempt to defeat the Kevlar plates in body armor. My question has always been - why can't we use a more effective round than the 5.56mm? I once had an E-7 tell me in Afghanistan that he wished he had his Fathers M1 from the Korean War so he would have some stopping power and range not present with his M4 carbine

There is a wide variety of rated armor. A level IV is rated for .30 caliber Armor piercing. I believe it would protect against a new 5.56 anyway.

My question would be at what range? Maybe we need to have a couple different weapons available based on the terrain of the battle. The M16 was developed for Vien Nam, and works well for the close quarters fight, if we go back to a defense of Europe scenario I would think that something with better range would be more desirable.

As for the ability to defeat body armor, I am thinking that the 5.56 has plenty of speed, if they produced bullets with tungsten inserts and new barrels to handle the heavier bullet that should defeat body armor.