also of interest is
how little contact there is between follower and round it seems to have almost
no effect on how the cartridges line up which leads me to believe that the guide
lips are the main factor in the proper magazine function.
Before the slide has moved rearward past the magazine, there is no contact between the top round and the feed lips. The center rail is pressing down on the top round.
When the slide uncovers the magwell, the top round moves up into position...above the bottom line of that center rail. If it didn't, the slide would ride over the top round and never pick it up. That's why you feel spring resistance when locking in a magazine with the slide forward.
We'll address that a little later, with photos that illustrate the two basic different feed lip designs and how they affect the angle of entry. Might be better on a separate thread since this one has kinda gone wide of the mark.