Try using 148 grain DEWC bullets, and an OAL of 1.35" or 1.36". (if you go shorter, they'll jam.) My Marlin '94 feeds those just as good as RNFP's and I can fit an extra one in the magazine.
You can use either .38 Special brass or .357, but they may look kind of silly in .38's with half the bullet and the crimp groove hanging out.
"The only way to stop a bad guy with a gun is with a good guy with a gun"