Very good actually. Learn something about aircraft then come back and continue discourse on this subject. Explosive decompression? Not unless you were carrying a Howitzer. No pistol caliber bullet would do enough collective damage to the fuselage. Airlines mandating frangible or bi-metal "aircraft safe" slugs would even get rid of the possibility of wrecking the avionics of hyd lines.
No. Punching a round, even a tracer round, through a gas tank is not enough to cause an explosion. Just a leak. Try shooting a gas can full of fuel sometime and you'll see what I mean.
I'd rather get shot in a gun fight with terrorists than sit there f*cking helpless while the plane gets crashed into a juicy target or lawn darted.
I know quite a bite about aircraft, for a laymen. Where in my post did I suggest explosive decompression? It's is a very practical thing to say that one guy with a handgun is going to have a very hard time disabling an aircraft. It is another thing entirely if the gunfight involved 10 people or more, no? You also discount entirely the fact that terrorists would be able to research schematics on the aircraft, take hostages, etc.
At the VERY best, you would have DOZENS of aircraft landing every week with cabins full of corpses.
Learn something about how human beings react under gunfire, then come back and continue discourse on this subject.
Statistics from war tell that 80% of the good guys will freeze or act erratically.
The remaining 20% who attempt to act decisively will be attempting to discern friend from foe in a confusing, chaotic mess. They will engage those of the 80% who act erratically, in addition to having to constantly check six to make sure that the bad guys don't have someone waiting for the armed passengers to react. They will be "armies of one," and about as tactically effective.
Meanwhile, the bad guys will have the advantage of superior situational awareness (knowing that your allies are Abu, Ahmed, and Mohammed, and that everyone else is a kuffar, really simplifies the tactical picture).
Firearms favor the few and organized over the many and unorganized. (Note: the American Indian tribes frequently had better weaponry than the US Army, but they still lost.) Better to have the passenger cabin gun-free (i.e., not even sky marshals), and to have the pilots armed and behind a door that takes some time to breach. (Stick firing ports into the door, and you can stack up dead terrorists in front of it all day.)