This is an indexing issue. I had the same issue with my setup, larger calibers it was a rare occurence but when you went to smaller calibers the problem really reared its ugly head.
When it hangs find where it is hitting and adjust the pawls accordingly. Tiny adjustments on the pawl screws can make a world of difference. It can be the difference between a machine with some hiccups and a smooth running machine. Sometimes all it takes is maybe a 1/32 or 1/16 of a turn on the pawl screw and everything is right with the world. One other thing I would check is make sure there is no debris between the subplate and the shellholder.
This post has helped me countless times on my machine.
http://thefiringline.com/forums/showthread.php?t=368171