A few questions for you experienced LRB casters...
Do you cast with "pure lead?
Do you cast with a bottom pour or a dipper?
Do you flux it?
What do you use for flux?
Do you stir it in and skim from the surface?
If you bottom pour, is it really necessary to flux, mix and skim?
I am trying to get as pure a lead ball as possible. I suspect that impurities in the lead pot affect the weight and accuracy of the ball.
1. Pure lead is all I cast with, as my suppository guns are on a prolonged vacation. They don't even remember the last time they got exercised. Besides, my press and my dies have long gone away.
2. I cast with a dipper as Rob demonstrated. Never heard it called compression casting, but it makes sense.
3. Yes, I flux with a dollop of pure beeswax.
4. Yes, I do stir it in and skim from the surface. It would be kinda awkward to skim from the bottom.
5. Never had a bottom pour furnace, so I don't really know the answer. But I would think that by stirring in the flux, one would catch the crud and it would float to the top. So, that is what I would do.
6. No offense here but I think you are trying to overthink the situation. KISS, my friend, KISS. Keep It Simple Sir.
My opinions here solely. Not to be confused with actual facts. But I think I am pretty close.
I also think that the larger and heavier ball you are casting, the hotter it needs to be. I remember when I was casting for my 8 bore and 4 bore rifles, I think I was near or over 800 degrees. It's been a while (maybe 19 years), so that might not be the actual temp I was casting at, but it was far hotter than for my .530's and my minni balls.
John (Bigsmoke)