I'm still pretty green at this boolit casting stuff, but I've had pretty good results so I thought I had a grip on it. Maybe not so much.....
I use a Lyman Big Dipper Casting Furnace and a Lyman ladle, one of those little ball things. I've always figured the best plan was to pour pour pour and keep pouring, until the ladle was empty. Let the excess melt just run all over the sprue plate and back down into the pot. I always hold my molds over the pot and pour them over it to catch the runoff.
Thought being, force that melted lead deep into the mold cavities for maximum fillout.
Seemed to work well, but I had problems with excessive flashing around the bullet bases and lead buildup on the bottom of the sprue plates. Figured this was just part of it.
Tonight, pot was getting low and dipping was getting tough, so I started just pouring enough to fill the cavities and make a little puddle on top.
Lo and behold, no flash on the bases! No sludge under the sprue plate! Much better boolits!
Think I may be on to something, so I refilled the furnace. Should be about ready now. Eh, so what if it's after midnight, I've got some 'sperimentin' to do.....