system
Given the following post, respond as if you're commenting on Reddit:
human
eli5 Why do militaries use depleted uranium in armor and ammunition

I have heard about depleted uranium shells and armor before but i wanna know why of all things you would use uranium as a metal compared to more conventional metal types.
gpt
It has properties that make it ideal for military usage, both defensively and offensively. It's also cheap and readily available.

**Density**- DU is very dense, which means it can absorb a lot of energy, like from the impact of an incoming projectile when used in armor plating. Conversely, as a projectile it can *carry* a lot of energy- meaning it can be highly destructive for its size when placed into the core of a conventional bullet or projectile.

**Anti-Tank Weapons**- A big challenge on the battlefield is neutralizing enemy armor, such as tanks. Not only do you need a projectile that will penetrate its thick armor, but you also need to disable it- such as by killing the crew inside. 
A DU projectile can do both of those things because it has two very appealing properties- it fractures on impact into razor sharp pieces and it readily ignites into ferocious flames when it does.
So with DU you have a high energy projectile that punches through armor plating, breaks into a swarm of deadly sharp spikes, and then incinerates the crew inside in a molten fireball. That makes it exceptionally appealing considering those rounds can be fired from a man-portable weapon.