Yeah, the inferno pistol, being specific to the first adventure of Iron Gods, is not in the PRD. It was created specifically to hand out what's essentially a low-powered laser pistol for low level characters, in any event.
I like the idea of a "low-level" laser. But, requiring a nanite canister (at 500gp)to fuel the thing is rough. When everything else uses Silverdisks, why would the device made for a lower level character have 5x more expensive ammo? It will take someone a while to build up the 5k for the pistol. Having to keep up with 50gp a shot is rough for even higher level characters.