I have used both H4831 and H4831sc interchangeably without issue. Hodgdon lists them both in the same description block on their website. SC version just meters and fills the case volume better.

Some primers are hotter than others. If using a magnum primer where it's not listed then you should consider it as adding 1 extra grain of powder to your load.

RC20 is correct in saying if you're shooting in the .2's and .3's you are doing something right.