SS 45 mag with bump on the follower

[crazy mark]

I bought 1 of several 45 acp mags that are SS and on the follower there is a small bump that the extractor groove lines up with. The only marking on the mag is an s on the floor plate. What is that bump for. Thanks, Mark

[deltaenterprizes]

It is supposed to stop the last cartridge from moving foreward from the recoil of the second to last shot in the mag and prevent jaming.

[crazy mark]

That makes sense. I have seen another that the bump is just forward of the case also.
Thanks, Mark

[unclebill]

that bump works.
i have a S.A.1911A1 and bought some KIMBER mags for it but that last round always screwed up.
i traded them for some S.A. factory mags with the bump and it has been smooth sailing ever since.