That blog post is on the weak side. The comments are a collection of flavor of the month with buzzwords (6.5, 6.8, blackout, scar etc)
There's no right answer for any of this. You're getting trade offs with any choice you make. Cost, durability, reliability, weight, energy, BC etc. Everyone is looking to get a better rifle for the mountains of AFG. They'll figure out what they want just in time to get it fielded for the next conflict in the jungle or built up urban areas. Then they'll want to go back to someting smaller.... You can't win.
Little Jack hit it on the head. Buzzwords. You will always be trading something off. I have seen what green tip does to human flesh from 15ft to several hundred meters away. If you are a rifleman in combat, the round is sufficient for killing, trust me. Seems like they want everyone to penetrate barriers or the magic man stopper bullet. The military is well organized for these things. Someone is hiding behind a small barrier window. Bring up the 240, or even create a good beat zone with a 249 or 2. No results? Send some 40mm thru the window. Still getting bothered? Time for the Gustav to handle biz. M4s in 556 are perfect for both close in house work out to 500m ish, depending on optics and if employed properly. I rather carry a double basic of 556, with my variable power Spectre DR and a 14.5 barrel to maximize energy than change to a heavier caliber, hump less of it etc. At 300m I am taking well aimed shots into the mountains, and yeah those green tips still kill at that distance. If I am doing house work, I love the nothing recoil and lighting fast follow up shots from the 556. We usually have a guy or three with a 762 SCAR in the mix as well for those well placed 800m shots into the mountains, but house work is significantly slowed down by the SCAR heavy doesn't matter who you are, not to mention you are carrying half the ammo. Introducing a new caliber seems like a waste of money to me, though I am sure it would make several people in Washington very rich much like the Army ACU fiasco.
I guess my opinion is that in the world of light weapons we have what we need to get the job done if there is someone in charge smart enough to properly employ the different organic resources we have. What we need to purge the military of all the political correctness and social experiments being forced into it. But again, this is just one guys opinion. Cheers all
So, after 50+ years of standardizing ammo among NATO and other "partner nations" we're thinking of leaving the 556 realm for ____" Is that was I'm seeing? Not saying other calibers are trash, but one word: Logistics. For a small number of specialized weapons, yeah, we'll always have that. For the mass majority, Nah. I'm sure the weapons/ammo makers will love the business, but........ Hey, I see what's going on here.