If you're using it in a 457, you don't need to worry about it. Those magazines were made for (I think) a version of the 4516 to correct problems that the early 4516 guns had. There's a thread in this sub forum on them. I forget the details of the issue, but it had to do with feeding, I think. That crimp at the top of the magazine with the yellow follower was part of that solution.

I have a 457 and have used those magazines without issue. One of my magazines with the yellow follower has the sternly worded warning,

FOR S&W 4516-1 NOT FOR USE IN S&W 4516 OR ANY OTHER REVISIONS OF M4516

I posted about that here and several members assured me that it was fine to use them in the 457.

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Can open, worms everywhere.