Shells are all the same

Posted by Mohoo on May 17, 2005

I could not catch this phrase "shells are all the same", and the context is as following:
It was a dangerous job. One day, Hemingway and two other reporters were driving a car near a battlefield. The car carried two white flags. But rebel gunners thought the car was carrying enemy officers. Hemingway was almost killed. He said, "shells are all the same. If they do not hit you, there is no story. If they do hit you, then you do not have to write it. "

help me ,please.