Well Rooster Ron Wayne will be interested in this as he has been hunting for one. If they are being made again he should be happy.
Did you unscrew the mag tube first? I am not familiar with the Miroku takedowns, but on the Chiappas you flip out the "handle" at the end of the mag tube and use it to unscrew the tube, then the barrel assy can be unscrewed. Or maybe yours is just really tight.