Most Inherently Accurate Full-Auto...

[BigBear]

I would think the BAR would be too "big" to be considered.... I would like to fire one some time though... but I think I might be spoiled on teh .50! lol.

[BPTactical]

Don't forget that one of the most accurate Semi Auto rifles in the world is built off of the G3 platform, the PSG 1. Basically a HK 91 with a bull, longer barrel, enhanced trigger pack and stock.

[Fredmisery]

I noticed nobody has brought the Uzi up since the original post. I have a Vector that is surprisingly easy to control on full-auto with amazing accuracy. Throw a green mountain barrel in it and crank up the cyclic rate with a rubber buffer and you'd be amazed at how much it improves the functioning of the gun. M16 is the same way, as long as I'm running a good barrel I think it's pretty darn accurate in full-auto, but again, I have manipulated the cyclic rate to what is most controllable for me and my shooting style.
Now bringing up the combat issue with 5.56mm I think the round is very effective through a standard M16 (M16A4 is what I generally carried). Most of the guys I worked with had M4's and a few with even shorter barrels, they might have a different opinion of the cartridge's performance, but out of a 20" barrel I think it works like it's supposed to at the ranges it was intended for. I would not have minded an M14 EBR, but wasn't available, my only choice was an M4 or M16, I chose the 16. AK's are fine for what they were designed to do, but over there I have to admit I kinda hated them