system
Given the following post, respond as if you're commenting on Reddit:
human
Could a cosmic ray set off ammunition or explosives?

I've read about how cosmic rays can cause errors in computers.     
I've also read about how they can damage genetic information.  

This got me to thinking. 

Could a cosmic ray set off the primer in a cartridge, resulting in a bullet firing unintentionally?

Or could a cosmic ray unexpectedly cause explosives to detonate?

I'm guessing it would come down to the amount of energy a cosmic ray could potentially deposit and how it interacts with something it passes through.     But I don't know much about either of those things.
gpt
You may have read that cosmic rays have very high energies. That's true, but incomplete: they have very high energies *for such a small particle*.

They can cause errors in computers because transistors have been scaled down to microscopic levels, so the ionization caused by cosmic rays is meaningful at that scale. They can damage genetic information because the DNA molecule is storing information at scale of a few atoms, so if ionization breaks the molecular bonds then atoms may recombine in weird ways.

But at a macroscopic level their energy is negligible.

Ok, there's an exception to that. There are some *ultra high energy* cosmic rays where a subatomic particle may have an energy equivalent to a fast baseball. That's really a lot, but at the same time, higher energy particles traverse matter almost unaffected, depositing only a very small part of their energy.

So no, they can't cause a bullet to fire and they can't detonate an explosive.

> the amount of energy a cosmic ray could potentially deposit

Lower energy cosmic rays are the ones that deposit more energy in matter proportionally to the distance they travel, and it is negligible at a human scale.

> how it interacts with something it passes through.

Matter is made of atoms, and atoms are full of electrons. When it passes through it kicks electrons off their atoms. This may cause weird recombination and modify molecules such as DNA. It can also collide with an atomic nucleus moving it out of its place - it implies something for highly sensitive electronics but not much for humans.

Also note that these things about errors in computers and damage to DNA are mostly a concern in outer space, but fortunately on Earth we're protected by the atmosphere. The radiation level we receive on the surface is low enough to say we don't have to worry about it.