Casting issue

[Sig]

I had cast about 300 or so .357 boolits a couple of days ago. When I inspected them prior to sizing I noticed about 10 of them with this abnormality. It looks like a chip in the front driving band. These were cast from 20:3 mix of pure lead & foundry type at about 700 degrees. The boolits were dropped in water from a Lyman 2 cavity iron mold. Any idea what is causing this?

[Calamity Jake]

The boolits have a heavy frost on them too, to much in my book. Mold and or alloy to hot
The tearing is caused by opening the mold to soon after the pour, slow the casting rate down so the mold won't be so hot,
Give yourself a count of 10 before opening the mold.
You can also cast with 2 molds at a time to control mold temp.

[Sensai]

I think CJ nailed it; too hot and too fast. Slow down a little and I think you'll be fine. :smile:

[littlejack]

Sig:
I have experienced the same thing before. As stated above, let the mold cool with the melt in the cavities a few seconds longer,
or let the mold cool just a little.
Also, the missing section seems to be in the same spot on each boolit. You may want to look and see if there is a small burr in the cavity, that is causing the boolit to "catch" in that particular spot.
Regards
Jack

[Sig]

Thanks all,
I'll slow down & look for a possible burr.

[Wilkie]

I've seen something similar when my mold/melt was too hot, trying to go too fast and didn't open the mold all the way. Same "rip" on multiple bullets like yours.

[Old Caster]

If you go too fast, it will cause a smear on the underside of your sprue plate also which will eventually build up and cause dragging of the plate.

[Spawn-Inc]

If you go too fast, it will cause a smear on the underside of your sprue plate also which will eventually build up and cause dragging of the plate.

i got that alot before i switched to a PID controlled pot. i still get it sometimes, but i go to fast. i wait until the melt/sprue just changes colour.