The best course of action is to remove the bolt cover and bolt before trying to insert a metal mag again. Then I have a better view of what is going on inside the mag well looking straight down from the top. Before I was looking through the ejection port with the rifle fully assembled and couldn't see much at that angle.
I disassembled the WASR this morning and tried to insert a Croatian metal mag with the bolt and bolt cover removed. It does give a better idea of where the metal mag is hung up. It looks like the top of the metal mag is too wide to pass between the flat metal bars that hold the sides of the mag in place. On my Zastava M70 ZPAP there are dimples stamped into the receiver for that purpose. On the WASR it is sheet metal pieces spot welded on either side of the receiver. Those pieces are a fixed width and determine the width of the mags they will accept.
I got a very fine three cornered file and lightly smoothed the edges on the Croatian metal mag to see if it would help. It didn't and the mag still wouldn't fit.I stopped right there. I'm not going to butcher the mag because it fits and functions just fine in my Zastava M70. I'll just accept the fact that my Serb/Croation metal mags can't be used in my WASR.
My plan is to keep shooting the rifle with the polymer mags I have that work with the WASR. My problem with the Serb/Croation metal mags doesn't prevent me from shooting the rifle.
I plan to try different types of metal AK-47 mags to see if I can find one type that works in my WASR. Thanks for any suggestions about what mags to try out.