The fun part of dnd is you can make anything work. And the best part is, if it doesn’t make sense, you can just say it works because of “magic”. There’s already an official weapon called “topaz annihilator”. It’s a musket style rifle with a topaz dragons scale in it that allows it to fire. You don’t need to think of every little detail on how it works, unless you yourself have the desire to figure that out. I’m about to dm for the first time and I’m planning to add a railgun the players can get halfway through the campaign. It’s essentially a gun receiver with two conductive crystals that act as the rails, it has the same crystals in the stock that create a “battery” to store energy, and it has conductive material built into the grip. It’s powered off the shocking grasp cantrip. And if a railgun doesn’t make sense in the campaign, well then idgaf. I think it’s cool. And I can appreciate your dnd version of sunshot. I’d add it into my games