He didn't account for his heartbeat. Whenever doing something like that, diazepam is necessary because your heart is beating a million times a minute which WILL throw off the shop for someone inexperienced.
His heart was beating so fast he missed the shot. He could have made America great again
In the novel I'm writing, the protagonist is cheating on her husband and on her way to the spot where she's meeting the guy her heart is pounding so fast she thinks her husband is following her (He's not), she thinks she sees his vehicle, (it's not even close to the make and model of the vehicle).
When she finally gets to the location she wonders how criminals do bad things because she's just breaking a little moral code and she can't hardly focus, she can't even think if she was really breaking a law