10mm but no 40 S&W?

[Rodentman]

Yes sir! I have a 9mm S&W 986, a 625, 310NG and 610. I use these for the same reason, to fire rounds that the autos don't like. There aren't too many but some. And the revolvers have no issue with lead.

 

[readyeddy]

I would get the 40. You have the dies, small pistol primers, and powder (same as 9mm and 45 ACP). Brass is plentiful and inexpensive.

And although the 40 doesn't get much love these days, that doesn't mean it's not a great cartridge.