But that little cartridge spring there after rides on top of the shell plate
It isn't intended to ride on top the shell plate. Bend it down a bit and it should ride in the extractor groove of your shell. The correct installation will allow you to remove a case after you have slide it into place. You have to rotate the case slightly to cause the spring to move to the side.
From your description, it sounds like yours it sticking too far in, and bent too high. In the proper location it really isn't pressing against the case at all, it is just holding the case from moving out any.