9mm stick mag question

[jsiver]

I have 4 of these magazines lying around, still in their wrappers, that I thought fit an M11/9. But when I went to use them they are to big for the Mac. I've tried them in every other 9mm smg I own and fits none of them. Has anyone got any idea what they fit? It holds 30 rounds...33 if I really jam them in.

 

[5.56RifleGuy]

They kind of look like mp40 mags. 9mm stick mags are hard to identify.

 

[5.56RifleGuy]

Mp38 maybe?

 

[SDC]

They look like STEN mags; single-position feed, with that shallow catch position on a wrap-around shroud.