>>63846726
From what I can read it was fairly expensive to make and while completely functional, didn't offer enough to be worth it.
Also something about it's shells being heavy for explosive weight (rockets will do that) which negated the advantage of it being a lighter gun.
They wanted to make an SPG version if it took off which I think uses it's advantages more than a towed application but I'm not the ordinance board
Here's allegedly footage of it firing used as stock footage in some old tv show

https://youtu.be/6bJ-XNYux_M?feature=shared