Making my own stainless steel pinstems?

Hello,

For a while I have soldering premade sterling silver pinstems onto
my stainless steel pieces. I want to switch over to making my own
findings from stainless steel but I am not sure what type to buy.

Looking at McMaster Carr it seems the various alloys of steel have
different properties. Could anyone tell me whether I should get one
that can be heat treated or not or one that is soft or hard? I’m
looking at.04" stainless wire to bend into a simple pinstem and catch
and then silver solder to a type 304 stainless brooch.

Best,
Jessica