Can't help with a source for store-bought cast bullets, been making my own since LBJ was president and never bought a single one. I will second the suggestion re: gas checks on stuff you're going to run at 1600 fps. Plain base .30 bullets start having issues with leading past 1400 fps or thereabouts, depending on a lot of conditions. If the distances are short, then low-vel plain base loads can do just fine. Longer distances almost demand more velocity unless you have tons of elevation adjustment at your disposal. Personally, I would cut to the chase and go with gas checked bullets.
I betcha Google-fu will locate suppliers.
Get thee a Lyman cast bullet manual too, if this is your first rodeo. Any of them published over the last 50 years will suffice as an intro.
Good luck! I wish our club had a "bang-and-clang" cast bullet match.
