If you really only need 1:112" twist (or thereabouts), could the forward motion of a wad be translated to angluar motion of a slug? Could there be enough imparted that the slug would begin to spin and remain spinning with the angular momentum.
After all...wouldn't a 45 degree angle give 50% forward and 50% rotational force (obviously you wouldn't need that much) initially.
Just for discussion....thoughts?