Seven prototypes were built and tested at Rock Island Arsenal and Aberdeen Proving Ground, Maryland.
The Army intended to develop a self-propelled variant designated the XM71 as the core weapon system matured.
It also had long trail arms and a base plate to pivot the system in common with conventional towed artillery.
The XM70's single shared long barrel has grooves indicative of rifling to spin the rocket to gyro stabilize it in flight to provide additional accuracy.
United States Patent US4353285 gives detailed technical explanation for Pacific Car and Foundry improvements.