The AKs are generally less accurate than the .223s in use. So it’s kind of moot. AK’s just don’t have the accuracy and aren’t so designed in the first place. They are designed first to be reliable.
I suppose if you chambered a 7.62x39 in a bolt action rifle it could be pretty accurate, but there are far better rounds for long range accuracy. The muzzle velocity of the 7.62x39 is just too low.
In a shorter 16” barrel the 5.56 is more accurate. So an AR is going to be more accurate than an AK. But if you do some work on an SKS with a 22” barrel it will be more accurate than either with a 16” barrel because of more pressure build and velocity. I can out shoot either with my SKS and 7.62 hunting rounds. So the rifle absolutely has a lot to do with how accurate a certain round can be. And so can the brand and weight of the bullet.