Depending on the cylinder throats and the groove diameter of the barrel, .224 might work without leading...

I usually size my revolver bullets to the same size as the cylinder throats which "normally" are larger than the groove diameter of the barrel (Sizing larger doesn't help as the throats will swage the bullet as it's fired. Sizing smaller almost always results in barrel leading.). For shooting cast bullets it is best to know the critical dimensions of your guns, because everything else is a WAG...