Unfortunately, therein lies a problem. Die makers, even Lyman for their M dies, do not offer anything like an adequate range of expander sizes. Which is why I had to take to making my own, as I posted earlier. Needs a lathe, (even a very small benchtop will do). Buy lengths of 9/16-18 threaded rod (McMaster-Carr #98957A407) and have at it. (9/16-18 is the internal thread in the M-die body. My plugs replace the Lyman adjuster screw and the separate screw-in expander with a single piece. Lots easier to make that way.) Believe it or not, I have three different expanders just for the .38 Special, because brass temper affects the springback and hence the final size. I pick the one that gets me the best fit for the batch of brass I'm using for my wadcutter target loads. It DOES make a difference.