I had one, a Bolo model, that had been bored to take the 9mm Luger. Mechanically a neat (interesting) design.
However, it was one of the most uncomfortable and PAINFUL handguns to shoot that I have encountered in over 40 years of handgun shooting.
The small size of the grip, the less than handfilling shape, and particularly the large slot for attaching the stock meant that it HURT your hand when you fired it. This was with standard 124gr 9mm ball (I never shot it with anything else).
In .30 cal, it might be a little less painful, but I would highly recommend wearing a glove. Its not the nerve numbing slam of a .44 Mag, but it was a sharp, painful bite to the palm, that actually hurt (me) more than the big .44.
Your experience might be different, just something you ought to be aware of.