I do not really like the round but here is what an Infantry Officer has to say about it when I asked him if he liked the 5.56 round and the M-16...
Its fine. small size of the round enables high magazine capacity. little recoil enables accurate, quick sustained fire. the slight recoil also contributes significantly to marksmanship. the damage with the small diameter round is caused by yaw, or bullet tumble, due to the high velocity of the round... or so some say...
I like the round for its accuracy charecteristics... and having witnessed for my own eyes "average" soldiers from other nations shooting side by side with U.S. soldiers... I can tell you this is a fact... american marksmanship is far superior to that of any "average" soldier from any other army I have seen... we train good shooters fast, and the slight recoil surely helps...
the round is at its best, like any round, for center mass hits... works well for your "average" malnourished terrorist at "average" ranges... In truth, however, I don't think the round would perform too well against an! enemy wearing body armor or even one that was wearing heavy cold weather gear...
Arioch7 here. There you have it. Personally, I have owned an AK-47 and appreciate that gun and the M-14 more but there are pros and cons to all things.
I still liked my AK though...
Er...about the M-16 "tumbling" rounds. This is more commonly called a "keyhole" strike, because of the keyhole shape produced on the a target as a result of the bullet tumbling during flight. NO rifle is supposed to produce keyhole strikes!
The reason the M-16 (especially the older ones) did this is because they were manufactured with excessive freebore, in order to facilitate a wide variance of manufacture's ammo. Excessive freebore (ESPECIALLY in semiauto rifles) causes the projectile to contact the lands of a barrel on a NON-CONCENTRIC axis. This causes the same effect as when you throw a football, and it goes all "wobbly". The bullet exits the bore on a less than perfect axis, and by the time it's travelled a couple of hundred yards (sometimes less), it's in a full fledged tumble.
It's a VERY bad thing to have happen as it destroys accuracy at longer distances, and renders an otherwise good weapon, ineffective and unsuitable even under good shooting conditions!
The newer A-2s, and A-3s aren't supposed to keyhole rounds. We've got a couple of Armalite A2s and they don't keyhole, but when I was active duty we used A1s that did.
My biggest gripe about our ARs is that the mechanics in their uppers are needlessly complex, and that it "craps where it eats". The tilting block, and gas piston/tube mechanism is widely used (except for with things like H&Ks blowback system), and I can't for the life of me figure out why they settled on the complex little system that the AR uses.
...having now complained about it I have to admit that a buddy of mine in an operational unit just returning from Iraq tell me that their A2s and M4s were VERY reliable and rarely malfunctioned.