[Dead-Nuts-Zero]

Somewhat new to casting, have about 6k bullet experience with 5 different molds, everything working great over several sessions in last year or so.

Using recovered INDOOR range lead that I melted & poured into ingots for later use, have used them with great success in bottom pour Lee pot.

Using same source/batch of lead mentioned above, I poured off a few bars into the Lee ingot mold while casting bullets and found that some of them would break when I dumped out the mold. The lead would crumble like breaking a cookie exposing sugar looking crystals/granules of lead.

When thin ingots are still warm, I can bend some of them while others break as described, all from same pot of lead.

Have I overheated the lead or under / over fluxed it with sawdust? I'm removing the slag after fluxing but remelts are not producing any noticeable amount of slag. Thinking I have cast hundreds of bad bullets I remelted & cast again with same results.

My next move is to abandon this lead & start fresh, but really want to understand what I'm doing wrong...ANY SUGGESTIONS???