noun
airsoft pellet; BB pellet
Small spherical plastic pellet used in airsoft guns. Common in hobby and recreational contexts.
サバイバルゲームではＢＢ弾を使う。
We use BB pellets in survival games.
このエアガンは0.2グラムのＢＢ弾に対応している。
This airsoft gun is compatible with 0.2-gram BB pellets.
サバイバルゲーム is the activity (airsoft skirmish), where ＢＢ弾 is used as the projectile.
From English 'BB' (originally a size designation for shot) + 弾 (bullet/pellet). The term was adopted into Japanese for airsoft pellets.