It was machine gun fire.

是机关枪在扫射。

Bullets were fed into a machine gun.

子弹已装入机关枪中。

Finally I've got used to my machine gun.

我现在已经习惯了我的机关枪。

The machine gun isn't taken down easily.

这机关枪不容易拆卸。

Because he has invented the machine gun.

因为他发明了机关枪。