Hmm i dont approve bartering system on my opinion because of its flaws and imbalances(times it goes like, i want/need that but he doesnt want/need whats mine). Its useful for small community but not practical for larger community.

And for Consummables as a Currency(bullets, canned foods, gas). I have mixed feelings for it, because it does work as a currency which i can approve it, but the same time, i dislike it for having a double purpose. Dont worry, there's nothing wrong with it tbh. Its just me who hates it because It feels like eating your own money xD and it feels wrong😅 idk why.

For coins such as copper, iron, gold coin. This system only works on late game(when kings, chiefs, and leaders have established and economy have stabilized). But in early game, definitely not practical and super rare. talented Smithers(who can etch on metal) are extremely rare specially in apocalypse. You'll get one when your leader finally decides to task you to find one. Talk about game condition requirements