The only gear I never really understood was the APX-6
transponder. I always kept a wary eye on that live round .45 shell
aimed at the Top Secret cavitron.

This cries out for further explanation. From context, I assume the idea
was to prevent the bad guys from reverse engineering the IFF and figuring
out a method to interrogate it. But was the self destruct mechanism
*really* a live .45 calibre shell?