counter
counter for parts, stages, installments
Used especially in the pattern 第〜弾 (e.g., 第２弾) for numbered installments of a series, project, or campaign.
人気シリーズの第３弾が来月発売される。
The third installment of the popular series will be released next month.
新商品の第１弾として、スマートフォン向けアプリを公開した。
As the first phase of the new product, we released a smartphone app.
counter
counter for bullets
Counts bullets, shells, or similar projectiles. Less common than 発 (はつ) in everyday speech.
犯人は拳銃に６弾を込めていた。
The criminal had loaded six bullets into the handgun.