"That was the first time I had ever fired that gun," he said.
Always, always, always familiarize yourself with a firearm. Especially one that is intended primarily for self defense.
In the video he was quoted as saying he had owned and shot guns for years, just never shot AT someone. Perhaps in this article he was misquoted, or perhaps while he had never fired that particular gun, with that serial number, he had fired one or more just like it.