Hell I was there. This was a proof of concept, not a finished product and was shelved until need.
Burn out was apx 20in, not yards, and, upon burn out, velocity was high. Energy about two to three times that of a 45.
It penetrated well on hard targets and tumbled on soft. Reliably was a problem.
Remember, any ammo you find today is forty years old and is loaded with a rocket fuel that did not have a long shelf life. Therefor any test today will not be valid.
With any new approach you must offer an marked advantage to the system in use or it will not be used, and apart from no recoil, there was none. Fire arms have a 500 year history and are vary, vary developed and any new system must overcome this.