My hot take on balance:
>guns chambered in 9mm should 6 shot (17 dmg)
>guns chambered in 10mm should 5 shog (20 dmg)
>guns chambered in 5.56 should 4 shot (25 dmg)
>guns chambered in 6.8 should 3 shot (33 dmg)
>guns chambered in 7.62 sound 2 shot (50 dmg)
This will literally fix all AR, Carbine, SMG, and LMG balance in a single pass.