IMO we as reloader's and caster's can make things too complicated. I know I have been guilty of this in the past. I now believe in the KISS system. If i were you I would do a couple of simple things. First shoot heavy for caliber bullets. A 180 or even 200 grain pill will work great in your 30-30. Keep your velocities aroud 1500-1600 fps as Lloyd said. Good WW will hold up fine at that velocity. I do not believe you need GC's at that velocity, I do not use GC's at that velocity(I pour a 180 for my 30-30). I think 3031 is a little fast-I like a slower powder, with better case fill. Some use wad's but I do not. I shoot open sights with all my rifle's that I shoot cast bullets in. I normally shoot between 1 1/2 to 3 inch groups at 100 yards, and I limit myself to 200 yards for hunting. Cast a bunch, and shoot a bunch. Every thing else will take care of itself.
I know every one talks about fancy alloy's, and the need to mix this and that in your alloy. I am not saying they are wrong, I just think they make it too complicated. Everyone talks about hardness, and brittleness. I know these are important factors. However I also hunt quit a bit with my 45-70, 30-30, and 44 mag rifle with my cast bullet's. I just hold the front sight on the deer's shoulder and pull the trigger. I have not had one deer complain about the brittleness yet, but who knows it may happen some day. Tom.