Casting Minie balls- what am I doing wrong?

[Steve499]

I can't seem to be able to get any consistency in my cast minies. I have tried everything I know of. I have had my electric lead pot all the way up, have had the moulds hot enough that the bullets are frosted, have tried every different way to introduce the lead into the mould that I can think of. The best results I have gotten is when I place the sprue plate directly onto the spout tip of my bottom pour lead pot. The weight variations have been much less when I cast in that way but there are still voids in the bullets. The air pockets are generally fairly well centered but vary in size, making weight variations which can't be good for accuracy. The bullets pictured are just a couple of rejects I cut in two. I don't know what particular technique I was trying when they were born.

Any suggestions?

Steve

 

[Manyirons]

Give yer mold a HUGE cleaning, acetone at least followed by a THICK candle-smoking on ALL parts, keep the mold on the pot and well heated, works for me!

 

[Mercerlake]

From your pictures, I have to agree that a thorough cleaning of the mold, smoking the cavity and base plug with an alcohol flame or wooden stick matches will help. Most likely this is the result of a cold mold, and / or air is being trapped in the skirt area of the mold. Is your mold iron or aluminium? It is more difficult to keep the skirt cavity hot enough with an aluminium mold and base plug. NEI has a good mold preparation compound that works very well with aluminium molds.