軍武

找到一篇介紹MP9的文章
http://www.smallarmsreview.com/display.article.cfm?idarticles=1435
裡面有這麼一段
Another point that is a factor here is that the MP9 stays in battery when making a contact shot when the operator places the muzzle of the weapon right up against the target. This point was well illustrated during a presentation to an Asian country’s navy who were responsible for boarding suspect freighters. In the close quarters, the operator chose to use his pistol as opposed to the MP5 for clearing the ship and had to make a contact shot with a pirate with his pistol. The pistol went out of battery and couldn’t fire with the situation quickly becoming a wrestling match until the operator’s partner could shoot the pirate at point blank range.

文章裡的"battery"是什麼意思？整段大致意思為何？