銃弾

1. Origins, structure, and basic meaning

• Structure: 銃弾, read じゅうだん, denotes a projectile fired from a gun; in the examples, it forms expressions for a bullet mark and a model bullet.
• Basic usage: It refers to a bullet mark at a fictional crime scene and a model of an old bullet in a museum.

2. Common pitfalls and similar expressions

• Bullet rather than firearm
  • It denotes the projectile fired from a gun, not the firearm itself; the examples are fictional or museum-based.