I remember getting good accuracy out of a mini14 using 69 grain match bullets (1 1/2 inches at 100 yards) and 2 1/2 inches with ss109. I can remember killing several groundhogs one year around a persons shed back in the early 90s using federal 69 grain match.
I also remember getting some decent groups with several handloads. However I also remember watching some hot loaded 52 grain match bullet disintegrate leaving the barrel. Of course that also happened out of a colt hbar sporter.
This gives you an idea just how much of an issue that 1 in 7 twist can cause with bullets less than 60 grains.
The skinny barrel is unforgiving in harmonics and barrel heat. However the same can be said of the M14. However an Ak47 has a lot of the same issues if not worse.
These were 180 series rifles I got this accuracy from.
A mak90 shooting 1 and a half inch groups at 100 yards? Good luck with that!