If he fired, dented the primer, and didn't go off, he is probably shooting reloads. If he is a competent, skilled person, some circumstance lead him to use someone else's reloads. If it is a serious situation, it didn't matter at the time, he racked the bolt and shoved in the next bullet. A Remington 700 holds 4 in the magazine and loads from the top with the bolt open in to a box magazine.