The guns were tested in July 1928 and proved that the twin-machine gun arrangement was unworkable. The A6E3, under construction, was fitted with a simplified design with a single machine-gun; it also had single cupola on the centreline of the turret. The AA-turret was removed from A6E1 but the suspension and the gunnery arrangements were distinctly inferior to those of the Mark II. It was decided to discontinue the type and use the three vehicles as test-beds for the automotive parts. In 1929, Vickers submitted three alternative suspension designs which were fitted to the respective prototypes; the one on A6E3 involved a fundamental reconstruction of the hull but none of the designs provided a stable gun platform. Only in 1934 was a satisfactory type was fitted by a specialised firm.