I have found with Lee moulds a soft alloy works best and I use 2 at a time when casting,
one starts to get to hot and cause trouble, put to one side and use the other,
they all come out close to size and no under size ones,
the old moulds are better as the new ones tend to have bending problems in the handles,
I do like there 6 gang moulds,
doctored a 300gr 452 so it drops 320gr 458 and it saves loads of time casting,
T