A good argument, I will give you that. I can agree on an extended shatter weapon, decidedly more suppressive than a Hwatcha, but I sideways disagree on the Fish. I'm sick of seeing Hwatchafish, utterly sick of it. It's so overdone that it's just pointless to think of anything else. It's a go-to for any new captain or a vet captain who doesn't really know what to take (or is drunk).
However, I will agree. Something like this might be better off as a suppression weapon, rather than the pseudo-torpedo that the Hwatcha is (Slow moving, easily seen, semi-easy to avoid unless at point blank range). On a Fish, it would work perfectly as a flank harrass, if you extended the range adequately to make it moderately dangerous, and very defensive on a Spire or Gally. From the (fuzzy) math that I did earlier, I'd say increase the ammunition amount and the reload speed, but I'd give it a somewhat small AoE for each round. That way it would reward hits and not firing randomly into an area.
However, that doesn't solve the idea of any kind of actual heavy piercer. Yes, I know, "paired with the Typhon, too OP", but isn't that what the Galleon is there for? It's built to be a major weapons platform with an extremely deadly broadside, but dirt turning. A double Hwacha broadside with a gatling topdeck is more than enough to cause death if it's a 1v1, and even in a 2v1 with a full hwacha gally if the gunner and the engie are in good sync. Not changing an awful lot WITH a heavy piercer, and how often do you even see the Typhon anymore? I only see it on noob ships, joke ships, or Jedi's ship, simply because he pairs it with the Mino and it still takes forever to kill.
Hwo about this for a heavy piercer: An actual Flak weapon. A weapon that you can change the ranging on to change it's arming time, say, from 1000 meters down to 250 meters. Once it hits arming time, it projectile-casts in an orb around it, dealing a pitiful amount of damage per projectile sent out from the burst. You'd only have the ability to hit them with half of the payload of said round, making the damage, overall, pathetic, but harrassing enough to be dangerous. It'd basically be a long range, even less accurate gatling at that point, where every second shot is missing the target. Interesting dynamic, low damage but easy to hit with, sub-range to the Flak while still being acceptable close range.
Any better, in this event? Note, I'm talking about a new weapon here, not what the Bofors should be. I cede the field to you on that, it's a better mechanic than simply double-shotting with a little bit of piercing. I don't know if it should be double shatter, but I can agree with it.