Well, let's think about it for a second.
If you can fit 12/13rds of 9mm into a 10rd .357/40s&w for $26.00.... Need I say more.
Unless of course it doesn't work, hence my initial post.
9mm Body Width: .391 40s&w Body Width: .424, that's a .033 difference.
Worth asking, don't you think?