This sounds like a hit registration issue, which would explain a lot honestly.
I wouldn't mind looking into accuracy, but damage would have to most likely remain or lowered if absolutely necessary to ensure the weapon isn't ridiculous . Regarding the Lore section, I tried my best to keep most guns "Lore Accurate" with how they fire, but exceptions have to be made when balancing between PvE and PvP. If we were running on Unreal or Frostbyte I could get behind recreating weapons to match almost as a direct copy, but with the limitations Garry's Mod imposes on us we have to be pretty strict when making design and balancing choices.
Note: I'm not saying I'm against "Buffing" the Z-6, I'm just stating it's a delicate line between being overpowered and being well balanced.
Edit: The suggestion is also kind of confusing as to what you're entirely asking for, I'd just rename it to "Buff the Z-6"