They were meant to wound and take 3 guys off the line. I always wondered why but after my buddy the 1st Sargent explained it, it made sense. That would be awesome if it were true. The .223 was chosen because it was the lowest cost "proven" round to make. The "wound channel" and "hydrostatic shock" is dubious at best. Similar to hollow point rounds. The gas rifles that Stoner made originally were designed for larger caliber centerfire cartridges like the .308. Not big at all compared the the years before when we used the 30-06. But still puts the smack down. And it worked better with the gas design. More pressure to tune with and you could use larger tubes with less chance of fouling. The biggest upswing is the amount of .223 a man can carry, regardless of the mag size. It isn't uncommon for a ranger to have 750 rounds strapped to him. In just projectiles(not case and powder) it goes from 2.6 kilos to 7.2 kilos from .223 to .308. 55 grain vs 150 grain. The .223 sucks though for most uses, especially in the smallest grain projectiles. It can't fight wind and basically relies on keyholing or tumbling to cause trauma. A hollow point on a deer is one thing, but even then some states banned the .223 as it isn't humane enough to kill white tail. But just a thick layer of denim has proven to make hollowpoints not expand as predicted. Not saying it's all flim flam and snake oil, just that the reliability isn't there. Finally, we don't even record data so well. I have never heard of a projectile hitting a soft target at a perfect perpendicular angle. Every ballistic gel test we use does it that way. If we even went to 20 degrees off a perfect T it would require an many many times larger gel structure.When judging impact on a target the only things we can rely on reliably are penetration, and actual projectile diameter. The argument of the 9mm vs the .45 ACP is silly. The argument of the .223 vs the .308 is silly. They are different rounds for different reasons. And in choosing on vs the other you give up many things. Usually the biggest is how much can I carry and how much will it cost. Because ultimately as we all know it's not just that the projectile travels down range, it's about that it is placed where it needs to be. They were meant to wound and take 3 guys off the line. I always wondered why but after my buddy the 1st Sargent explained it, it made sense. That would be awesome if it were true. The .223 was chosen because it was the lowest cost "proven" round to make. The "wound channel" and "hydrostatic shock" is dubious at best. Similar to hollow point rounds. The gas rifles that Stoner made originally were designed for larger caliber centerfire cartridges like the .308. Not big at all compared the the years before when we used the 30-06. But still puts the smack down. And it worked better with the gas design. More pressure to tune with and you could use larger tubes with less chance of fouling. The biggest upswing is the amount of .223 a man can carry, regardless of the mag size. It isn't uncommon for a ranger to have 750 rounds strapped to him. In just projectiles(not case and powder) it goes from 2.6 kilos to 7.2 kilos from .223 to .308. 55 grain vs 150 grain. The .223 sucks though for most uses, especially in the smallest grain projectiles. It can't fight wind and basically relies on keyholing or tumbling to cause trauma. A hollow point on a deer is one thing, but even then some states banned the .223 as it isn't humane enough to kill white tail. But just a thick layer of denim has proven to make hollowpoints not expand as predicted. Not saying it's all flim flam and snake oil, just that the reliability isn't there. Finally, we don't even record data so well. I have never heard of a projectile hitting a soft target at a perfect perpendicular angle. Every ballistic gel test we use does it that way. If we even went to 20 degrees off a perfect T it would require an many many times larger gel structure.When judging impact on a target the only things we can rely on reliably are penetration, and actual projectile diameter. The argument of the 9mm vs the .45 ACP is silly. The argument of the .223 vs the .308 is silly. They are different rounds for different reasons. And in choosing on vs the other you give up many things. Usually the biggest is how much can I carry and how much will it cost. Because ultimately as we all know it's not just that the projectile travels down range, it's about that it is placed where it needs to be. I still wouldn't mind getting an ar-15 type platform in a .308