from the old forum:
I just ordered my first mold (mass produced), to get my feet wet as I've never casted before. I also ordered a RCBS dipper for ladle casting. The bullet mold is for a .458 cal 400 gr FN (#457643) and I plan to use straight WW's. Anyway, I have seen some previous posts where you recommended opening the sprue plate and ladle hole to allow a better pour and thus better bullet. I couldn't locate the posts, so could you be kind enough to advise on the proper hole sizes?
** The pour orifice on RCBS ladles is about 1/8". That's pretty small, plus it will get partially plugged with dross in use unless you flux religiously. 3/16" is more to my liking, perhaps even a little larger.
You might want to start out small and gradually work your way up one drill size at a time, because the larger orifice increases flow dramatically, and at first it seems difficult to control. After a while, you get used to it.
The pour stream should be about the same diameter as the hole in the sprue plate. Some sprue plate holes are not big enough. However, the sprue plate hole has to be carefully countersunk, so you cannot merely drill it larger.