That is a solid arguement Darcs, but even the standards a a tad different between bottle caps and bullets. Bottle caps are just shiny baubles, with no real use, as also played out in one of the fallout games (3, or new vegas, I forget) they could be manufactured. It would be pretty bad if that 3 bottle cap beer went up to 120 bottle caps because some douche face was making as many as he could every need.

Bullets on the other hand, aren't technically a trade medium like dollars, cents, rupees, or bottle caps. They are a useful item, as you stated. A useful item that can be spent, or becomes destroyed upon use, thus creating demand for more without the excessive stockpiling. This is still technically just barter. I may not have made it apparent the bullets are the widely used "bottle cap" system. But I did say it.

[quote=@Aeonumbra]
World runs on trade and barter, no currency system but bullets are widely accepted, high grade being worth more.
[/quote]

I do agree with you however that the rarity of the bullet does determine its worth. Dirty > High grade > Laser / Plasma > Heavy / Special. One may not have the gun to use the very expensive ammo with, but it's the prospect that one 'could' have the gun, or just spend it, in which case the before mentioned prospect still comes into play. Bottle caps existed with no other purpose than a trade medium, and its rarity was supposed to maintain its value. Bullets have more purpose than just trade, but their wide availability and usefulness, eg: high demand, makes them the "money" for this world, without actually calling it that.

But for the most part, we agree with each other. I just don't see them as a trade medium, rather they are an item with a usefulness compared to that of water or air. What's the point of breathing all that free, irradiated air, if a mutant dog chews your legs off. I see them as a barter item with their value weighed against their usefulness and demand, technically maintaining a steady economy with bullet trade.