Negatory on GPS
I've done a little work with GPS.
I work with a guy who actually dabbles in that part of the electronics world.
And he's a shooter.
His response?
*Laughter* RFID, maybe. GPS? Not in your dreams. (Long technical discussion ensues.)
The biggest barrier, as mentioned above, is the power requirement.
Now, if "THEY" somehow manage to re-task RFID scanners in stores, install billions (with a 'B') of them in cities everywhere, you might have a prayer of tracking an RFID chip.
Even then, the chips are too easy to disable.
So, just from a logistics point of view it's not happening.
Now, if I set up a database where I keep the serial numbers of every piece of gear that I assign to some region, and follow them from issue to return, that would qualify as electronically tracking the gear under current definitions.
By the time they solve the science needed to keep track of every lousy gun out there, you may be assured we will have other things to worry about.