I'm curious, therefore, why the lack of consensus? Is there any evidence inconsistent with the bolide hypothesis? Or is there just no positive proof whatsoever (e.g. some type of meteor residue or other) so it can never be conclusively demonstrated?
When anything combustible is aerosolized and mixed with oxygen, it allows it to explode. This is how thermobaric explosives work https://en.wikipedia.org/wiki/Thermobaric_weapon see also https://en.wikipedia.org/wiki/Dust_explosion
Gunpowder doesn't need oxygen, but it burns instead of exploding. If there was an initial set of fires and smaller explosions that dispersed unburned gunpowder and wood/grain dust into the sky, once it was dispersed a flash could have spread through the dust cloud and created a huge explosion as described. This theory would explain both the initial disturbances and the huge explosion at the end, but I don't see it mentioned anywhere.
Perhaps the passby tore the roof off the armory and sucked black powder into the air, and then the impact shockwave caused a fuel/air-like explosion?
Also note that the description is by survivors, so the sequence of sounds maybe different away from the impact.
That was my thought too, especially with the description of the initial rumbling noises. Gunpowder burning in a small space might well provide the energy needed to disperse something flammable in a cloud above the armory which could then be ignited at some interval after it was created, providing a fuel-air explosion above ground level which would explain the over pressure damage without burning, the shape of the mushroom cloud, and the magnitude of the explosion.
it seems a bit improbable that a bolide would just so happen to hit the armory. Given that bolide events are rare to begin with, the low chance of hitting a military building is enough to make me skeptical.
I have no idea what contemporary chemical explosives were extant, but if there were any plausible agent I would favor that instead.
Only black-powder. Nitroglycerin, the first practical explosive more powerful than black-powder, was invented two centuries later.
Well, isn't the probability of hitting the armory identical to that of hitting anywhere else on the planet?
On the other hand explosive materials accidents happen where big amounts of explosive materials are stored, and there's few places in the "anything else than armory" category so the event is more likely.