RE: Rifle powder in hand pistol rounds?
I doubt it would work. They need big cases and long barrels to be effecient. They probably wouldn't have enough pressure. I would be concerned about a hang-fire. I don't know if it would be dangerous or not, but I would always err on the side of caution and assume it would be.
And if you did it the other way around (pistol powder in a rifle case), you may just blow up the gun.