8 BORE
50 Cal.
Who cares about the hi tech crap if the mould makes good bullets use it.Actually, aluminum conducts heat almost as well as brass or bronze.
The 1000 series of aluminum has a conductivity of 135 BTU/ft/hr and 6061 aluminum has a conductivity of 125 BTU/ft/hr.
Wrought brass's have a conductivity of 135 BTU/ft/hr and pure copper has a value of 226 BTU/ft/hr. (Higher = more heat moves thru the material).
The thing is, the mass of the brass or bronze alloys is much higher than aluminum (brass/bronze is much heavier) so it takes more heat to heat up a brass or bronze mold.
Due to this, brass and bronze take much longer to cool down.
Beyond this picky information, I agree with everything else you said.
Who cares what its made out of.