Did any of you see the Mythbusters episode where they pressurized a DC-9 and fired a SIG P226 at and through the sides of the aircraft? They determined that no amount of shooting in any location of the side of the fuselage would cause an explosive decompression great enough to seriously affect the controlllability of the plane.
They had to use FBI explosives to create sizeable hole in the side of the plane. Needless to say, a catastrophic structural failure caused by a 9mm bullet is unlikely, according to their tests.