It is not a chip, it is just firmware and/or drivers. As for definite information, try scanning money sometime, or copy it if you have a combination scanner/printer. There is a specific yellow dot pattern on currency to avoid having to teach scanners/printers about all currencies in the world. Have a look, it is not hard to see once you know it is there. If you remove the dot pattern, the counterfeit money is not detected as money by machines (not that most people could make money that even the cheapest machines would accept, dot pattern or otherwise).
If you manage to get a scan, you can print it if you enlarge or shrink the notes, then the pattern will not be recognized -- but people get suspicious when they receive double-size currency.
It would be a lot more difficult to tell the firmware not to scan/print guns. A gun does not depend on yellow dots to function.