Yankee Weapons introduced the Excalibur in a limited production run and delivered the first models to Star League Defense Force units in 2520. Designed to deliver long range firepower, the Excalibur features a large Grizzard Gauss rifle that extends through a dummy hand on the 'Mech's right arm. The long rifle barrel makes the 'Mech resemble a sword wielding medieval knight, hence the name Excalibur.

       The Excalibur is one of the fastest 'Mechs in its weight class, thanks to its powerful Ford 350 XL engine. A Grizzard Gauss rifle, known for its accuracy and endurance, an LRM 20 rack, and an Artemis IV fire control system constitute the 'Mech's long range armament.
       Like many other 'Mechs intended for long range combat, the Excalibur carries a relatively small amount of armor--only seven and a half tons. This relatively light protection keeps Excaliburs out of close combat and forces them to withdraw from combat after taking a few hits. Some observers maintain the Excalibur's light armor is a serious design flaw, but Yankee Weapons counters such criticism by pointing out that the Excalibur was never intended for close combat. They further contend that the 'Mech's McArthur antimissile system provides ample protection against incoming missiles.
       The Excalibur distinguished itself in Operation Smother during the Reunification War, though many of these units were then destroyed in the close fighting conditions common in the Amaris Civil War. Records show that units equipped with the Excalibur, when used in conjunction with other 'Mechs, had a higher kill ratio than other SLDF heavy 'Mech units.

       Currently the Yankee Weapons design team is working on a new variant of the Excalibur, the model C1. This variant replaces the original design's twelve standard heat sinks with ten double sinks and adds two tons of armor, primarily to the front torso and arms and legs. The C1 also replaces the anti missile system with a Defiance B3M medium laser, added to the left arm.

       Currently, only the Com Guard and the mercenary unit known as Rhonda's Irregulars field operational Excaliburs. In a welcome move, however, Yankee Weapons Systems has reopened their plant on New Earth and should have the first new Excaliburs rolling off the assembly line by March of 3058.