銃
じゅう · juu · JLPT N3 · noun
gun
🔫 銃 = metal 金 + fill 充: metal you fill, then it goes juu like a bullet's zoom
The left part 金 means metal. The right part 充 means to fill or load and also supplies the reading juu. So a gun is literally loaded metal. Bonus sound hook: juu shares its sound with 十 (ten), so think ten rounds loaded.