I have not fired that particular gun, which appears to be a "one off" home build, but I have fired several selective fire pistols, 9mm, .45, and 7.63, with and without shoulder stocks.
But I have a problem. In spite of deep concentration and going into prayer and fasting, I have not been able to think of anything more useless. The stocked .45 pistol alone, without serious ear protection, is a sure path to deafness. An auto version will hit nothing with anything but the first shot except at bellygun range.
I'll pass.
P.S. A standard magazine lasts less than a second.
Jim