Never heard of it (not that that means $hit) but the engineer in me thought that was interesting. I looked around and on another forum a gentleman describes the same thing:
The link to that quote is http://ohioccwforums.org/viewtopic.php?f=10&t=2291&p=28223 although there doesnt appear to really be any more info on that subject in the thread.
So it could be that the plastic is pushing the round up in a funny way that the all-metal version isnt. Are the tops of your two mags different? Not the follower but the top part of the magazine frame where the "lips" curl in...
Excellent sleuthing -- many thanks! +140 or whatever. I'm still scratchin' my head over the phenomenon -- the mags are virtually new when considering overall usage even though they're decades old from off the production line. I'll check the lips (closely) on the tops of the two magazines and compare them to the two (older still) all-metal follower-types that DO function "normally".
Thanks again.