There is currently no reason to use the AK-74 over the AKM.
AKM hits harder, is cheaper, more controllable (lower firerate) and kills more consistently, AK-74 is a spray and pray and hope that your enemy doesn't have more DPS than you.
I was using the AK-74 for the first few days of the Nov 8 patch then switched to the AKM - very noticeable difference afterwards.
- Increase the damage of both weapons so they can kill in 1 shot to the head, chest & stomach (like Insurgency2014)
When both guns are as lethal as each other, damage doesn't even become a factor in weapon balance, and this increases the other characteristics of the weapons itself to make them more distinct from each other (weight, rate of fire, recoil).