You'll get a lot of opinions on this. I began working with cast bullets in the 9mm in the late '80s. Found many, many, cast bullet designs that did not shoot accurately and leaded the bores of various guns, probably because most were undersized to begin with.
The most accurate 9mm bullet I've found to date (works well in my three 9mms) is cast from an obsolete Lyman .38 Special mould #358212. It's a 150 grain roundnose. I use wheelweight alloy and size to .358" I use Bullseye powder though HS-6 works fairly well.
S&W autos often have tight bores; whether .358" will work in yours, I have no idea. Regardless, the fattest diameter bullet that will freely chamber will be your most accurate. I don't know what is available from commercial casters, but I would try to get sample of several bullets and diameters if I was serious about accuracy.
Most 9mms can be surprisingly accurate, but it's often a frustrating experience finding the right bullet. Many give up and make do with something inferior. Good luck in your endeavor-
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