但是不好用的弹药可以用 "ineffective ammunition" 来表示。

"Ineffective" 是形容词，意思是 "not producing the desired effect or result"。"Ammunition" 是名词，意思是 "bullets, shells, or other items fired from a gun or other weapon"。

例句：

The soldiers found that their ammunition was ineffective against the heavily armored tanks.
中文翻译：士兵们发现他们的弹药对重装甲坦克没有效果。
The company recalled the ineffective ammunition due to safety concerns.
中文翻译：公司由于安全原因召回了不好用的弹药。