system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5, why do we make bullets out of lead instead of a harder metal like steel

Is it just that lead is cheap? Or is there a reason to use a softer metal like lead? Because I feel like a harder metal would do more damage no?
gpt
A couple of different reasons, not the least of which being a denser but softer metal will do more damage when it hits a soft target.  Another reason is that lead has a much lower melting point than, say, iron or steel, so anyone could make their own musket balls back in the day.

But a big reason these days is because you want a softer material than steel as your bullets to keep from damaging the barrel, especially if the barrel is rifled.  Lead and copper won't cut into rifling grooves, while steel will wear them down over time.