Gerald Bull and Naval Ordnance Station Indian Head tested an 11 in (280 mm) sub-caliber saboted long-range round[6] in a stretched 16"/45 caliber Mark 6 gun in 1967.

[7] The Advanced Gun Weapon System Technology Program (AGWSTP) evaluated a similar projectile with longer range in the 1980s.

LRLAP featured separate projectile and propellant portions and was to be highly precise, with a circular error probable (CEP) of 50 m (160 ft) or less.

[4] By early 2021, the navy was exploring replacing the AGS on Zumwalt ships with modules to carry hypersonic missiles.

[9] In March 2022, it was announced that both AGS would be removed from Zumwalt destroyers to enable installation of tubes to accommodate Common-Hypersonic Glide Body missiles.

The AGS is mounted in a turret specifically designed for the Zumwalt-class destroyer with fully automated ammunition supply and operation.

A primary advantage of the AGS over the existing 127 mm Mark 45 5-inch gun which equips most major surface combatants of the US Navy was to be its increased capability for supporting ground forces and striking land targets.

[12] This was intended to increase the utility of vessels equipped with the weapon, especially in areas in which the US Navy exercises absolute sea supremacy.

[4] Other projectiles were examined to replace the LRLAP, but since it is the only munition designed to be fired from the AGS, the barrel, software, cooling system, and automated magazines would have to be modified to accommodate a different round.

[11] In particular he noted that the BAE Hypervelocity Projectile testing, a cross-service 127 mm (5-inch) naval and 155 mm land, low-drag self-guided Mach 7-capable round originally intended for railguns, was achieving range close to the original LRLAP specification while having superior rate of fire and accuracy.

[16] Shortly after the USS Zumwalt (DDG-1000) was commissioned but prior to weapons system integration,[17] the U.S. Navy moved to cancel the LRLAP due to excessive cost.