Reply #54: Magical thinking, IMO. You can already get guns with integral locks

[benEzra]

or put them in a safe (my choice), and the other device needed to operate them is the key (or in the case of a safe, a combination).

The problem with fingerprint readers, magic decoder rings, and other esoterica is that a firearm is a high-temperature, high-shock, high-g environment not conducive at all to electronics, they function for decades or centuries, and they MUST be absolutely reliable and not delay the legitimate use of the firearm more than 0.1 second or so. Non-bypassible authentication systems capable of operating for decades INSIDE a firearm while providing 0.9999 reliability under adverse conditions with multiple users and 0.1 second access time would cost many times more than the firearm itself.