In the early morning hours of Aug. 4, outside a crowded bar in Dayton, Ohio, a gunman fired at least 41 rounds in 32 seconds, striking 26 people. Nine of those victims died in the shooting.

The gunman was able to fire so many rounds so quickly because he used a 100-round magazine. That meant he didn’t have to stop firing to reload. If police hadn’t already been on the scene and able to return fire so quickly, many more almost certainly would have lost their lives.