Guns in a world without metal or magic?

Clickbaitey title, genuinely sorry. More specifically AIRGUNS.

Would ceramics and wood still make this possible?

How vital would metal be specifically in the process of :

-constructing gas chambers?

-filling gas chambers?

I know that a non-metal world will have no process of machine-filling the chamber in the typical sense, but I am more than okay with the "guns" of my world being so inconvenient in make and usage that they are hard locked to certain social classes

As for the development of proper air tight-seals, I know sap/ancient mesoamerican style rubber may do the trick

In terms of barrel wear, we can just assume that the broadest part of the ammo (the part that will rub the barrel) is softer than the wood/ceramic of the barrel, and that the business end is thin and needle-like, or hangs on the outiside of the barrel entirely

I'm thinking:

Giradoni style shape - (drawing upon proven stuff)

Completely ceramic body - instead of wood for weapon longevity

primitive rubber - at edges where an airtight seal is necassary

psedo-arrow ammo- normal arrows but with a dug out back end to catch air

But I would love for a ceramics expert to chime in with how impossible exactly (not how reasonably *feasible*) to for a ceramic in a non-magical world whose technology developed without metal to hold these kinds of air pressure