Look at the black mag on the right a 10 round 84f mag. Note the metal above the arrow.
Look at the silver mag to the left, a 13 round BDA mag. Note that the metal above the arrow is gone. I had to file it a bit to keep it from cutting. This is a true browning BDA 13 round mag.
The Mag on top is a Mecgar 13 round that lacks the metal piece, but the metal is thicker in the body so no big deal.
I have about 6 or 7 mags with this tab of metal broken or missing. They were all bought about the same vintage so I expect that they were all from the same run.