Controls are identical to predecessor. The XM6A3E1 is an experimental Paternian main battle tank equipped with an oscillating turret and an automatic loader feeding from two five-shot drums. This drum can be reloaded from within the vehicle itself, although this is an involved process involving the TC and the gunner.

It was developed as a proof-of-concept machine and a competitor to the KRIEG-designed XM6A3E2 AUTO, which featured a KRIEG-designed conventional welded turret. While the machine performed well, with its longer-barreled XM68E1 providing greater muzzle energy than the XM5 cannon offered by KRIEG, the XM5 cannon offered greater energy retention over range, a more effective HE shell, and potential for upgrades in the future.

However, the XM6A3E1 had several advantages. It could take advantage of existing stocks of 105mm gun ammunition, where the XM5 cannon required new ammunition to be developed. In addition, its drum-based autoloader design allowed for ammunition to be switched rapidly with the ability to select which drum to feed from. Rounds could be replenished from the hull, with 32 additional rounds of storage.

In addition, the autoloader could be mounted to the turret roof, where the KRIEG design was more complicated as the result of using a conventional turret. As a result, when the XM5 120mm gun was specified, it was easily adapted to the machine, with two four-shot drums due to the larger caliber, thus removing one advantage the KRIEG machine had.

Both machines would later receive more powerful engines, being reclassified as XM6A3E3 for the Bandit design, and XM6A3E4 for the KRIEG design. This was later changed to XM6E4R1 and XME4R2, respectively. The XME4R2 featured an improved autoloader design, from a carousel to a rack and elevator system.

After exhaustive trials, it was concluded that both machines were comparable in capability and cost. However, the KRIEG proposal was a simpler system, it's autoloader had greater capacity, could switch shell types as easily as the drums, could be replenished more quickly, and could be adapted to existing hulls more easily. It was also more reliable with the 120mm gun, as it was designed with this weapon at the outset, where the Bandit proposal was forced to modify their system to accommodate the larger gun, resulting in some reliability issues. The XME4R2, would be accepted by the Paternian Army as 120mm Gun Main Battle Tank M6A4 AUTO Ardent.

While the KRIEG design would become the backbone of the Paternian Army's tank force for 30 years, the XM6A3E1 and XM6E4R1 prototypes were converted to the M6A4 AUTO standard. The former turret was preserved in the Paternian Armored Museum, where the latter turret was scrapped.