JBS,
The Missile Theory is just that theory - just like the centre tank and cargo door - ALL theories.
First the reason that the B747 nose separates is that it is without doubt the weakest part of the fuselage structure with hi diff loads and contour change. Hence the station 41 FAA AD.
Second, like yourself, the eywitness flying the coast guard helo was n air force major with 48 vietnam missions and on the program was quite forceful that from his experience
the first 2 explosions were definitely HE.
Finally after all the debate the military did several test firings of stingers mainly to check the visiblity effects. the film showed the firings and related them to the eye witness reports. Many were identical !
** Still an open mind !!***