I had this problem with my .45 and a Hume type case feeder (its not marked, so I am not sure who made it). It would feed .45's perfectly with the plate turned upside down (set for .38 Special), and I finally discovered that either the cases were a little too long or the distance between the bottom of the feed trough and the bottom of the plate was too short. Eventually I milled a small amount from the bottom of the top plate, and everything has been fine since. Otherwise, you can trim your cases.