Since devs seem to balance weapons more or less at random, here's an idea. Make your balancing goals objective based. Here are some examples:
Minigun - mid tier, 2 bursts mid-range to kill a powerbuild in leather/metal mk1
Avenger Minigun - top tier, 2 bursts mid-range to kill a powerbuild in metal mk2/combat, BA/ca mk2 kill when lucky - if not 3 bursts
Plasma Grenade - mid tier, close combat - depending on the way sneak is either something that kills no matter what or who on full AP attack with knockdown or something that kills no matter what or who on full AP attack with a possibility of escaping
Molotov - utility weapon for killing shit prone to fire more efficiently than frag/plasma
Flamer - another utility weapon
... etc. I bet you get the drift. Moreover, make the goals open source to get quality feedback from advanced players as far as balance goes and from everyone else as far as fun factor goes.
The rationale for this suggestion is the fact that most changes to weapon balance seem to be based on theorycraft that honestly is far removed from reality. Or I'm just delusional and you've all thought about the issue this way - if so, let's discuss how do we want each weapon to behave in descriptive terms instead of "nerf" or "buff".