On the other hand, Kyle Defoor, Marcus Luttrell, Paul Howe, Kyle Lamb and numerous other SEALs that also fight alone say they prefer the 5.56 even when some have access to the SCAR H with a 13.5" barrel. Using Mk262, 75gr TAP and especially Brown Tip 70gr, the 5.56 has made leaps and bounds.
If you head over to SOCNET and Lightfighter, like I mentioned before, you'll see verified SEALs and Army SF swearing by 5.56 and stressing that no bullet will do better if you can't put them where you want them. The only one that has really complained about it at all was Paul Howe, but he was saying how m855, which was made to deal with an organized military wearing body armor, was zipping through the enemy in Mogadishu and he'd have preferred a different bullet.
Right now with the Army's Improved Carbine competition, there's some talk about why nobody submitted a 6.8 or 7mm Murray. The answer is they'd have to profile a quarter million rounds for the test then, if it should be adopted, it would cost the Army BILLIONS of dollars to replace it's current supply of 5.56.
Many experts claim that 6.8 would be a better choice as it could replace both 5.56 and 7.62, but the actual gain within 300 yards would be minimal. On top of that, only in CQB is it dire that they stop right now. At 300 yards, most bullets will take them out of the fight.
Those threads on the Imroved Carbine has a number of Special Forces guys talking about how effective 5.56 is and the only ones who think it needs replaced for engagements within 400 meters are those with no experience with the better bullets and those with little training.
There's a reason the Russians developed the 5.45. It's not because the 7.62x39 was too good, it's that the 5.45 was a better match for Americans armed with 5.56. They had a better chance of gaining fire superiority SI the lighter round that they found wasn't really any less effective on enemy combatants.
I'd love to see the 6.8 make its way into our fighting rifles. It would allow the use of shorter barrels as standard with an effective range farther than 5.56. It provides a little better barrier penetration compared to 855. When comparing to 70gr Brown Tip though, the difference is less. There's a number of good things that could come from a 6.8, but the cost would be ridiculous for an incremental increase in terminal ballistics.
If the money spent on this nonsense was put into training and a superior bullet to 855 and 855a1, I think we'd see much less complaining about the 5.56.