Advanced Gun System The Advanced Gun System is a naval gun system under development by BAE Systems Armaments Systems ( formerly United Defense ) for the " Zumwalt " - class destroyer of the United States Navy . Production has started ; the first magazine was delivered to the U . S . Navy on 25 May 2010 . Originally designed for mounting as a vertical gun , this 155 mm ( 6 . 1 " ) caliber gun has since been slated for mounting within a more conventional turret arrangement . The AGS is designed to offer a weapon system capable of delivering precision munitions at a high rate of fire and at over - the - horizon ranges . As a vertical gun system it would only have been capable of firing guided munitions ; the turret mounting will allow the use of unguided munitions as well . Description . The AGS uses the same 155 mm caliber as most American field artillery forces , although it is unable to fire the same ammunition . Instead , a new range of ammunition is under development for this weapon . The gun barrel is 62 caliber s long , and is able to fire the entire magazine ( 300 + rounds ) with an average rate of fire of ten rounds per minute using a water cooled barrel . The AGS is to be mounted in a turret specifically designed for the " Zumwalt " class destroyer with fully automated ammunition supply and operation . The turret itself is designed to be stealthy , allowing for the entire length of the barrel to be enclosed within the turret housing when not firing . Ammunition . The development of new ammunition for the AGS under the name Long Range Land Attack Projectile ( LRLAP ) is one of the major advances offered by the AGS program . The munitions are to be highly accurate , with a circular error probability of or less . Lockheed - Martin conducted a flight test of the munition in July 2005 , reporting a flight distance of . The LRLAP ammunition features separate projectile and propellant portions . Total weight is , including a bursting charge of . The maximum length of the combined munition is , amounting to about 14 calibers . Operation . A primary advantage of the AGS over the existing Mark 45 5 " gun which equips most major surface combatants of the US Navy is its increased capability for supporting ground forces and striking land targets . With a 10 round per minute capacity , it offers the ability to deliver firepower close to that of a battery of six 155 mm howitzer s . This will increase the utility of vessels equipped with the weapon , especially in areas in which the US Navy exercises absolute sea supremacy . Usage . The AGS is currently only slated for inclusion on the " Zumwalt " class destroyer although it could also be included in other future ship designs . No plans have been revealed to retrofit it to current ship designs . The shortening of " Zumwalt " procurement to three ships increases the likelihood that BAE will attempt to market AGS to other programs . History . There has been research on extending the range of naval gunfire for many years . Gerald Bull and Naval Ordnance Station Indian Head tested an 11 inch sub - calibre saboted long - range round in a stretched 16 " / 45 Mark 6 battleship gun in 1967 . The Advanced Gun Weapon System Technology Program ( AGWSTP ) evaluated a similar projectile with longer range in the 1980s . After the battleships were decommissioned in 1992 , the AGWSTP became a 5 " gun with an intended range of , which then led to the Vertical Gun for Advanced Ships ( VGAS ) . The original DD - 21 was designed around this " vertical gun " , but the project ran into serious technology / cost problems and was radically scaled back to a more conventional 6 . 1 inch Advanced Gun System ( AGS ) . One advantage of this move was that the gun was no longer restricted to guided munitions .