They might work but not reliably. The 9mm is much shorter so they might shift a little. Also since the 9MM case is tapered, the more rounds you put it the more the nose of the bullets will tilt down. When shooting the gun, you will find that the rounds will nosedive right into the feedramp. I had used something similiar. I was running 9x21 loaded long as the 38 Super rounds in the Hi cap mags. If I loaded 10 rds, then most of the time it worked. Too much problems so the gun will be in 38 Super.