Near the end when Peter and Joe speed up to the store robbery and Peter's eyes are irritated, he shoots his gun wildly. One shot goes through the windshield then curves to go back out the windshield again.
When Peter wildly enters the convenience store and holds his gun on the robbers, Carl then pepper sprays him, attacking him despite Peter acting in support of him to stop the robbery. It makes no sense to act against Peter at that time in this way.