[Daisuke]

I agree that some of the debuffs are pretty insane (dat sonic shell) and definitely need some tuning (perhaps moving certain effects around to overcharge) however I want to make the point that strong debuffs on 1-hit guns are a good niche for them and that theme should definitely be kept in mind when adjusting them.

Even with these buffs, they don't actually surpass multi-hit guns in terms of raw damage so having better bonuses on their shells puts them in a really nice category and gives them a different playstyle which I find really neat.

Multihit guns are all about crit, sparkdrive, and high damage potential by consistently reapply shells (so they tend to avoid overcharge)
Onehit guns are all about manually charging up, hitting you once for really good damage while applying a strong debuff, and then either charge up again, shoot you normally, or use cooldown if you overcharged to reload.

And I say manually charging up over trying to crit and spark drive because being tight on skillpoints means you might not even have it and the nature of 1 shot vs 4 shot guns in terms of crit makes it a bit unreliable which can be punishing if you rely on your charged shot effect.