High Quality Content by WIKIPEDIA articles! The 3-inch gun M1903 was a rapid-fire breech-loading weapon, with 360-degree traverse. The M1903 gun was an improvement of the M1902 seacoast gun. The 3-inch gun was placed to provide fire to protect submarine mines and nets, and to protect against motor torpedo boast within its range. The 3-inch gun was mounted on a pedestal mount that bolted into a concrete emplacement that provided cover and safety for the gun`s crew.