bullet, twang, flip, snap
弾 centers on the sudden release of tension: a bullet shot from a gun, a string twanged on a bow, or a quick snap or flip. The meanings all share the idea of something springing or being propelled sharply.
弾 is the modern simplified form of 彈. The older form combines 弓 (bow) with 單, which likely contributed the sound and the idea of a sling or projectile. The modern right side 単 is a simplification.
A bow 弓 beside a simple sling 単: picture pulling back a bowstring and releasing it to shoot a bullet or make a twanging snap.
For ダン, imagine a bullet hitting a metal target with a loud 'dan!' sound: dan -> ダン, and the bullet snaps forward from the bow.
counter for parts, stages, installments, etc. (of a story, series, project, campaign, etc.)
bomb
to flip; to snap; to flick
to play (a stringed or keyboard instrument)
to burst open; to split open; to pop
ammunition; ammo
bullet; shot; shell
gun; pistol
oppression; suppression; pressure
trajectory; line of fire
bulletproof; bombproof
bullet (from a rifle)
singing to one's own accompaniment; reciting while playing the shamisen, biwa, etc.
being shot; being bombed
hand grenade; grenade
censure; denunciation; (verbal) attack; blaming
warhead
elasticity; flexibility
impact (of a projectile); landing (of a bullet); striking
to spring; to bound; to bounce