Earl,
I flew with the USAF for a couple of years on exchange. Who exactly are the USAF protecting themselves from by carrying a firearm? Who is going to hyjack a C-130 or C-141???
FD security needs to be started well before any passenger arrives in the cabin. Let us be absolutely honest about security before 9/11. It was incredibly slack and was an open invitation to someone who wished to exploit it. Of course that statement is said with the 20/20 vision of hindsight. However, while I was down in the states, I can honestly say, I was staggered by how bad it was.
FD security is all about prevention. There is no way that anyone should be able to get onboard with a weapon. If they do then the flight deck door must remain closed regardless of what happens in the cabin. Arming us is not the answer, it is only a very dangerous band-aid solution.