[Retric]

That video is on Sporting Ammunition which is relatively low energy and shotgun shells which are reasonably safe in a fire. A rifle round cooking off is significantly more dangerous though without a barrel it’s below a normal handgun round, still the difference from that video is still shocking.

Edit: It's mostly true that ammo in a fire will just pop and maybe just throw a little brass a short distance.

BUT from that fire I'm witness to the fact that ammo can also "fire" with enough force to go through steel 50 cal ammo boxes and continue through such things as walls and cans. There were bullet holes through the shop's paneled and insulated tin walls. https://www.thehighroad.org/index.php?threads/ammo-in-a-fire...

I will admit I may be overstating the humidity issues, my personal experience was 15 year old ammo in Florida shed which had issues but clearly YMMV.

[bacondude3]

Do you have a source for that? I don't really understand why shotgun rounds would be less dangerous, particularly if rifle rounds are more dangerous. More powder = more dangerous would make sense to me, but that doesn't sound like what you're saying.

Some parts of Florida are more humid than Appalachia, so maybe the difference between 75% and 95% humidity has a greater effect than 55% to 75%.

[Retric]

I was told the rifle rounds where more dangerous, but not why. My suspicion is the plastic tube around a shotgun shell loses strength before the round is hot enough to go off ~200C. Though it’s probably more complicated.

As to humidity, I don’t know it might be just extreme humidity or it could be humidity + temperature, or perhaps we had a bad case of ammo to start with.