Working up a load is just what it sounds like. Every firearm has a sweet spot, and working up a load is location of that spot. Where handguns are concerned I work in .2 grains on the ladder till I find what I like. Rifle is at .5 grains on the ladder. On a rifle I shoot two 5-shot groups per step and check differences. For handguns I shoot 2 full magazines and then work from there (AFTER DETERMINING EVERYTHING OPERATES CORRECTLY). Distance varies, but handgun is usually 10yds. for my testing, and rifle with jacketed is 100yds for jacketed and 50yds for cast, then I stretch out from that point.
As for how far a cast bullet can be shot, I load my .40 with a variety of cast, but they run parallel with jacketed in all respects. My cast HP loads perform better than jacketed factory loads.
"Why is is called Common Sense when it seems so few actually possess it?"
Guns only have two enemies: Rust and Politicians.