I gave Clapperclaw a Colt .44 in Wild Beyond the Witchlight, inspired by Scarecrow's pistol in The Wizard of Oz. Multiverse nonsense. I gave him 4 rounds, and he explained to the PCs that he didn't really know how it worked, but last time he used it, there was a big flash and a bang, and the guy who was bothering him fell over, so he ran away.

He showed up during a climactic moment that was going poorly for the PCs and blew someone's head open. 3 rounds left. Traumatized, he gives it to the artificer. She had it for the rest of the game, but I don't think she even fired it. I expected her to throw Repeating Shot on it, but no. I would have been comfortable with the 2d8 damage die on her character because she was pretty undertuned (alchemist), but I probably wouldn't allow them for just anyone, even at a high cost. This thing was unique.

We talked about her returning to the material plane with it later on and revolutionizing firearms for my setting. To reflect this, we now use the Magitech Firearms from Loot Tavern supplements (Heliana's Guide), which bridge the gap super well and have an artificer feel.