Powder charge: What should I use if I'm getting misfires?

30 grains is too light for reliable ignition in most calibers. For .45 or .50 caliber, 60-90 grains of FFg black powder is a typical starting range. Swiss and Schuetzen are preferred brands. Work up from 60 grains and find what groups well. Underpowered loads cause delayed ignition, poor accuracy, and increased fouling.