The repetition of the phrases becomes tedious, just as their lives are tedious; the repetition also calls attention to them and emphasize their symbolic importance.
The trainees do not have a psychological point of balance in their lives. Living in barracks, apart from wives and sweethearts, they are living an unnatural kind of life. Their lives are incomplete, like their equipment. By learning the parts of the rifle, they are preparing to kill and be killed. They are living a regimented life. Being raw recruits, they are awkward. Their lives are tedious, as expressed by the repetition of dull phrases. The rifle is a mechanical instrument, and their lives are likewise mechanical.