"Theese bullets came out really nice, hardto believe the other makers are that much better, is it the steel vs aluminium. "
The other mold maker's products are not "better", as such. It's easier and therefore less costly to make a high quality mold with aluminum blocks than iron but the bullets don't care. The only real difference is the iron molds ability to withstand physical abuse and there is no justification to a user doing that anyway! IF I was a high volume caster I suppose I'd prefer the long term durability of all iron molds but I'm not, so the Lees suit me fine. I have a small collection of iron molds too but I find it easier to produce better bullets, on average, with the aluminum molds so that's what I use most of the time.
If there is a difference in precision, it goes to alum molds; the mold cutters last longer without resharpening, which makes the cutters ("cherries") smaller, so the cavities can be economically cut very close to the proper diameter and bullets not need to be sized for excellant performance. The high cutter wear on iron demands the expensive new cherries start larger and cut bigger cavities for bigger bullets that MUST be sized down for proper fit. The sucessive cavities will get smaller as the cherries are resharpened until they get tossed out.
Different casting alloys and, to some degree, different molds cast better near a certain temperture. A bit of experimentation allows us to find that temp. A thermometer helps us stay there for the whole session and return to it later.
Most casters can afford to own an iron mold or two. Lee makes it possible for the less wealthy of us to own many more molds, and even some gang molds too! AND, there's no great danger of the blocks/cavities rusting; that can be nice.
