I've been trained to shoot, and am familiar with firearms, was even shooting yesterday. But I would be against guns in the cockpit, most pilots would hate the idea and as many people pointed out there are other ways of dealing with hijackers, particularly if they are locked outside closed flight deck doors.
In any case, the hijacker might just resort to the classic movie scene and hold a knife to someones throat, trained as I am. I doubt if I could get a clean shot in the circumstances.
In any case, I've come to believe that any attempted hijack in the near future is doomed from the start. Pax and crew will automatically assume it's a suicide mission and act accordingly. We would have nothing to lose. I also suspect the incidence of air rage will decline too for much the same reason. The next drunk that storms the cockpit will undoubtedly die. With or without firearms.
That's the new reality.