I have a ruger Sr 40 which is a copy of
A glock with the floating barrel .I tried the tunicate shaped bullets they jammed but worked in my carbine .I think I either need a round nose or a big flat point not sure as anyone used cast bullets in these ?

I use a lee bullet in mine 175gr swc have shot thousands of them. With out trouble.

I make sure I run the cases through a Lee bulge buster die.

look on any of the commercial bullet makers sites for their rnfp meant for the 38-40.
get it sized to 402 if possible.
they all use the same magma engineering mold so it don't really matter who you get it from.