Firing full auto from the standing position is the province of the submachinegun. Since they weigh the same as the regular battle rifle and only fire a pistol caliber, they are controllable from the standing. Sort of: you still have to lean forward a bit to offset recoil. The AK and the StG-44 before it started the used of "intermediate" rifle calibers meant to blend submachineguns and rifles and therefore higher rates of fire from walking troops. Most of us who have faced the AK in combat know that unless the first shot hits you, you're golden because the rest will sail above you to threaten treetops. We did the same thing with the M16 but the Mousegun had the advantage of a much lower recoil impulse and therefore greater controllability from the offhand. I have fired the M16 a lot since Vietnam and the full automatic versions were very controllable - but not necessarily very lethal or effective against protected targets.
The army pushed towards a concept called "walking fire" in the '80s that somewhat amusingly, included the M60 machine gun. The last version of the M60 - the M60E3 - had a little thin wispy barrel and a vertical foregrip so you could stand and chunk away with it. The problem was, as anyone with half a brain already knew, machine gun barrels get hot - really hot - and the M60E3 barrels melted. Literally. I had a desk full of S-shaped M60E3 barrels with bullet holes through the side of them. That's why the Corps went to the M240 to replace the M60 and nobody proposed "walking fire" anymore (mainly because standing around in a firefight more or less guarantees death).
I am a bit of fossil now but if my country called me to serve with a rifle, I'd still lean towards the M14 because it, like me, is an antique - but a really effective antique!
It should be pointed out that just as the M16 isn’t the same rifle it was in Vietnam, the AK isn’t either. A lot of the AK’s inherent accuracy issues have been dialed out over the years, though the massive bolt carrier slamming back and forth still causes issues endemic to the platform.
Starting with the AK-74, muzzle climb on full auto became much less of an issue - not just because of the 5.45x39 cartridge that version fired but because they put a very effective muzzle brake on the end of the barrel. Then they backported that idea to the regular AK 7.62x39 line and found it to be even more effective. Our guys in the Sandbox who’ve played with captured AKs or borrowed them to test from coalition troops they’re serving with (Poland and other former Eastern Bloc countries that have joined NATO and/or come to the Sandbox prefer their modernized AKs) have discovered that at this point the major limitation on a modern AK on FA isn’t the rifle, it’s the operator. A reasonably well trained shooter with a modern-spec AK is going to be about as effective on FA as a correspondingly skilled shooter with an M16 on FA at this point. The old rule of “first round missed, so will the rest” of an AK on FA sadly (for those that have to oppose it) doesn’t apply to a modern AK in the hands of a trained shooter any more.
Fortunately, the Taliban, ISIS and most of our other opponents in the Sandbox are *not* well trained. Then there’s also the “inshallah marksmanship” they’re prone to, which doesn’t help them. You really don’t want to see what the Russians can do with them, though.
Here’s a modern spec AK in 7.62x39 (the AKMS spec with the now famous ‘slant brake’) and an AK-74 clone in full auto: https://www.youtube.com/watch?v=oJnJhhX_Nqs
You can see the difference between the AKMS and later and the older spec rifles - here’s a professional using an old-spec AK: https://www.youtube.com/watch?v=cosc-RO_oMg
That simple slant brake and the slightly more complex brake on the 74 has turned out to be shockingly effective.
FYI, the M60E3 was not the end of the line for the M60. The M60E4 or Mk43 continues in US service and the M60E6 has just been adopted by the Dutch. Among other things, they fixed the Stellite lined barrel. https://en.wikipedia.org/wiki/M60_machine_gun#M60E4.2FMk_43_Mod_0.2F1
AKMS-ish spec rifle with the AKMS muzzle brake, one of the older vertical foregrips (yes, the Eastern Bloc got these too) from before RIS caught on and an RPK drum on FA for 100 rounds.
https://www.youtube.com/watch?v=bXUlLIeNT6A
Again, not at all doubting what you said about the weapons as they were back when, just showing that the AK improved just like everything else did in the intervening time. :D