Okay, I almost posted this on the LAST "Replace the weak M16 with the almighty M14" thread, but it was too long for me to bother.... So here I go...
The idea of "replacing" the 5.56 with a 7.62 because it has a longer range is EVERY bit as short sighted as saying "let's replace all the 7.62's with 50BMG's" because it has an even longer range.
In the military, EVERY military, there are multiple weapons in multiple calibers to fascilitate the completion of a variety of tasks.
Since MOST of your fighting is done under 200 yards, then MOST of your troops get 300 yard rifles.
I do not disagree at all that perhaps 1 man in 10, or maybe even 1 in 5 should have an AR-10, along with the extra training and accessories required to CONSISTENTLY engage and neutralize targets at extended range. But to take away everyone's M16 and give them an FAL because your pet cartridge is the .308 is just not realistic.
Unless you're fighting an enemy 700 yards away that are all equipped with FAL's, then they are just as handicapped as you are. 7.62x39's effective range isn't even as far as the 5.56, so why are we loading down the AVERAGE soldier with a heavier rifle, heavier ammo, and heavier recoil at the expense of 10 less rounds per mag just so EVERYONE has the "theoritical ability" to reach out and touch someone?
It's just not practical.
Maybe I'm a big sissy, but My M1A went full-auto on me once. It scared the begeezus out of me. The first round went where I aimed, the second round hit the top of the target, and rounds 3, 4, and 5... well who knows for sure... they were headed at about a 45' angle upward
Now maybe your 110lb girlfriend likes your semi-automatic FAL, but then again I always considered the M1A's recoil to be mild to moderate on semi-auto too.