noun
tear-gas gun
A firearm-like device that fires tear gas, used for riot control or self-defense.
警察は暴徒に対して催涙銃を使用した。
The police used tear-gas guns against the rioters.
催涙スプレー is a small handheld tear-gas spray for personal defense, whereas 催涙銃 is a larger gun-like device.
Compound of 催涙 (tear-inducing) + 銃 (gun).