New caster problems

[glockky]

I have cast for a few sessions now and keep running into some small problems. When I first started casting 38 bullets using just straight COWW I had not trouble at all. Then I tried 44's and some 30cal bullets. All of these were usable but I had to get my temp up to 700-800 deg to get good fill out. Then a lot of my bullets were really frosty and had undersized gas check shanks.

So my question is do my COWW just not have enough tin in the mix? Will adding tin allow me to cast at a lower temp and get good mold fill out? thanks for the help

[bangerjim]

Add tin. WW"s have around 0.5% tin (average) and may not be enough.

I add some to all my COWW casting soup. More tin should allow you to cast at a cooler level.

banger

[alfloyd]

You only need to add 2% tin at the max.
Less may work OK.

Lafaun

[runfiveslittlegirl]

a little tin will help, however the real issue is mold temperature.
also how you fill the mold will make a difference, aligning the sprue hole and filling each cavity quickly will help on the longer skinny rifle boolits.

[btroj]

Yep, mould temp.
A too hot mould gives really frosted bullets and can make them undersized too.
Turn the heat back down, preheat the mould, and get a good rhythm going.

Each mould needs a slightly different rhythm. Long skinny cavities are different in heat exchange and loss than a short fat one.

In general I find that smaller bullets need a faster rhythm to keep mould temp up while larger bullets need slower to allow the mould temp to stay in the proper window.

I use a small fan to help cool the mould before cutting the sprue. It help prevent the mould from getting too hot.

Stop thinking melt temp, think mould temp. Hot lead into a cold mould gives wrinkly bullets, you tell me which matters more?