Clone the Bill Blaster NPC (npc-21), but give it a different fired NPC type?

[Lithobraker]

I'd like to make an identical copy of the Bill Blaster, except that it fires a custom NPC. That's it, but I don't see NPC-21's code anywhere in the files. Is there some resource I can reference, or is this not possible?
The handbook, as far as I can tell, doesn't have any relevant information.

The reason why I want to do this is because Generators don't aim for the player like Bill Blasters do, and they lack gravity+the general utility of an NPC.

[Lusho]

The NPCs below ID 293 don't have a lua file because they are vanilla 1.3 NPCs, I'd recommend waiting until patch 3, since the Bill Blaster NPC got augmented there, or using Core's SMW Bill Blasters

[Lithobraker]

The NPCs below ID 293 don't have a lua file because they are vanilla 1.3 NPCs, I'd recommend waiting until patch 3, since the Bill Blaster NPC got augmented there, or using Core's SMW Bill Blasters

Figured it'd be something like that. So they're baked into the .exe, then?
I was going to use Core's SMW Bill Blasters, but they don't stop firing when you get close- which is why I wanted to recreate this.
I'm unfamiliar with lua, so I don't really know how to add that behavior, either.

[Lusho]

I guess the best thing should be waiting until patch 3, there you can choose the projectile of the Bill Blaster, and yeah, they're hardcoded inside the exe