I'm not sure how that explains anything.Do you know what the range of an RFID chip is? We're talking 30 feet max, and that requires a really sensitive reader to excite the chip and read the SN off of it. A GPS receiver would tell the gun where it was, but that doesn't help either, as it is a receiver, not a transmitter. Since the RFID reader would know where it was, what the heck use is a GPS device?
Also, in saying that these "chips" were on each weapon, are you saying that the government was providing these modified guns to the dealers? Where exactly would one install a GPS chip? Where would it get its power from? If it also had some kind of transmitter, where was its power source? How much range did it have?
You see, someone just waving their hands and invoking RFID and GPS as some kind of magic doesn't really work in the real world. In order for this to make sense, we need less magic, and more actual facts.
The weapons were fitted with transmitters and the Mexican government knew about the program. They would trace the signals when the weapons came across the border and where they were headed.
I remember a thread not long ago that had a lot of facts with links, but did not reply or bookmark it for future reference.