Bullet
noun
Back in the day, a bullet was a circle shape. So, this word is bullet.
だんがん
The 弾 part is okay, but you never learned the on'yomi reading of 丸, which is がん. When you shoot a bullet, you are using a gun (がん). Bang!
俺は弾丸の雨をとても上手くかわした。
I expertly dodged a spray of bullets.