Was there not another member that told you that Frankenstein's monster started life as a 7.62 x 51 mm. How long will it take to achieve Stoners Original Work?
Stoner hated the 5.56 idea. And many others did at the time (and obviously still do). When I was old enough to consider the argument, the 5.56 had already distinguished itself, so I've always come down on the side of the 5.56 as a GENERAL PURPOSE RIFLE CARTRIDGE.
Now that last capitalized part is the important part.
Me personally, I really like the 7.62x39 for an assault rifle; it has more of what I like in a fighting rifle round.
But guys like you and I are gun-geeks, and riflemen. Being much better trained, generally more competent at arms than your average recruit, we tend to want more from our rifles.
But your average recruit, and the vast majority of soldiers are not gun people. They are people who are in jobs where they must carry a rifle. Most recruits are scared to death of a rifle, and training them on something like an M14 to be truly competent take a long time, and even after they have been sufficiently trained…give them a 5.56 and their scores will go up. What's more, their effectiveness in combat will go up; as studies by nearly every military in the world who has studied such things have shown. Again, this is general issue.
For most of what an infantry does, the 5.56 does it very well. So well in fact, that 9 out of 10 times a special operations group goes into the field, they carry their M4's. And it's that way for most every military and special ops group around the world.
After a while, you have to come to terms with that.
Now all that said, the US Military's decision to just dump the 7.62 was a dumb one. Certainly the M14 program was a train wreck, and canceling it was clearly the right thing to do. Switching to the M16 was the right thing to do (but certainly not HOW they switched). But to just completely drop the idea of a 7.62 battle rifle…that was dumb. All the other NATO nations pressed their old 7.62's into the designated marksman roles when the need arose, and the G3 & FAL did, and still do a good job in those roles. The M14 on the other hand…When pressed into DMR roles, it served well…for about a year. Then all the ugly issues started to come right back up, and the US Military was desperate for a replacement, which they got with the M110. But the M110 was pressed into service a little too quickly, and it too had issues (but fortunately those issues were one's that could be dealt with).
What kills me is how SPOT ON the Russians have been with their assortment of weapons they have available to their infantry and special ops units. It has taken a good 30+ years for the US to catch on, but what we have seen in the latest batch of wars and conflicts, is the need for an array of weapons for when the mission calls for a different weapon.
The Russians have their SCHV in the 5.45 and they're generally pretty happy with the performance of that round as a general issue round. But when the mission calls for it, they have a good number of other weapons available. Their issue squad auto is the RPK, but they do have racks of RPD's available should they need them. Each unit has a number of RPK gunners, as well as designated marksmen with the SVD rifle in 7.62x54. For the intended role, the SVD is a pretty darned good rifle. It is NOT a sniper rifle, it's a designated marksman rifle; and it does that job pretty well. RPK's are available, as is the various suppressed 9x39 rifles (and the US is now considering some suppressed .300 blackout rifles).
So for general issue, the 5.56 is pretty hard to beat. But the notion that it can do all missions is just as fool hearted as the notion that the 7.62 NATO can do all missions.