Yep, I use heat too. Because material thermal expansion is inch per inch per degree temperature change, the inches of the center hole of the drum are more inches than the axle flange, so the drum expands more for a given amount of temperature rise than the axle flange does. This same principle is also why heat helps to loosen stuck fasteners.
Many Land Cruiser drums have 8 x 1.25 holes that you can just screw in an 8mm bolt and it will push the drum right off. Not sure if mini trucks/runner drums have these too.