I tried to take advantage of the ambi mag release on the new Glock Gen 4 by switching it to the left side.

Unfortunately, this makes it impossible to use any older magazines. I thought this probably wouldn't matter to me, as I don't have any Glock 9mm mags and could start fresh.

However, it seems to be impossible for me to locate any true Generation Glock 4 magazines (with cuts on both left and right side). Does anyone know where to buy these?