I am imagining a society that uses gun powder and maybe bronze to fire stone projectiles, is this silly
Cannons yes, handguns no. Handguns were made possible due to advances in steel metallurgy, and no alloy of copper-zinc-lead is remotely as strong as steel per unit weight.
Also, both the oldest surviving cannons from china were hand guns.Actually, the Tannenberg gun, an extant early fifteenth century stave-mounted handgun, is cast bronze. I don't think you can make successful muskets from bronze, but basic handguns will work.
Cannons yes, handguns no. Handguns were made possible due to advances in steel metallurgy, and no alloy of copper-zinc-lead is remotely as strong as steel per unit weight.
didn't they make cannons out of brass back in the day?
No, because the discovery of gunpowder is not necessary linked to the use of iron. The ingredients of gunpowder are saltpetre, charcoal and sulfur, ingredients that do not require the use of iron. In OTL gunpowder was discovered in Byzantium as an alternative to the already known greek fire (since aprox. 500 AD), but it could have been discovered centuries earlier. OTL is not the best TL in regards of technological discoveries....
I personally think that any society advanced enough to figure out gunpowder to the extent they are building cannons would have already discovered iron deposits and realized it is more economic to make steel weapons instead of bronze.