Get the Accurate Powder manual that has excellent reduced load data. Do NOT deviate from listed loads until you have had Considerable EXPERIENCE with reduced loads. Another thing that can happen with reduced loads is when the primer flash goes the entire length of a cartridge that is loaded with slow burning powder, they coat the grains of powder to retard quick ignition....the flash just partially ignites the powder, just enough to kick the bullet into the rifling...then the rest of the powder kicks off with an obstuction in the bore...KaBoom! Pipe Bomb!
I use AA's XMP 5744 exclusively for reduced loads with only published data from the Accurate book. It has worked safely with everything incuding a 300 Ultra-Mag with cast bullet loads.
Smaller cases can be loaded with small charges of pistol powders like Red Dot and Bullseye. I have not used the bullseye much for these type loads, but have used the Red-Dot with things like .357 and 7.62x39 with heavy for caliber cast bullets. 4-6 grs usually works well for me for fooling around.
Also....reduced loads can put your brass through a lot of grief. It is recommended to keep the brass separate from what you would use with normal loads.
ALWAYS MAKE SURE YOUR BULLET HITS THE TARGET WITH ANY REDUCED LOADS! If you have ANY doubt whatsoever that your bullet did not leave the barrel, remove the bolt and LOOK down the bore. If you have a rifle that you cannot look down the bore....use a cleaning rod to make sure it is clear.
Also...with reduced load experiments...the is always the chance that you will stick one in the bore....Cast bullets are far more easy to drive out with a rod than HARD JACKETED BULLETS, and a bolt action or break barrel single-shot are highly recommended in case you DO stick one. That way you can pound the bullet out whichever direction is the shortest distance to get it out.
BE VERY CAREFUL.