I've been visited a time or two by the TF and the last two times were caused by some H2O in the scrap and a primer in the bottom of the bucket
Yesterday she was back but arrived too soon to do any damage. I had been given almost a full box of cast bullets and decided to melt them down--they had been sitting open in a garage and the lube was gone on most of them and they were covered in sawdust and the like
Went on and ran down the pot (18 lbs used) and at the end when it was time to refill I dumped the entire box into my casting pot Pro-Melt 1. Now I have a pot full of bullets and am waiting for them to melt.
After about a 1 I hear 3 TF pops--my guess is some primers got into the box along with the dust and dirt.
Since I had about 5 inches on solid bullets on top of the melt all I got was the pops of the primers and a desire to change my shorts.
I did quickly put the lip on and weighted it down with some ingots just to be safe.
Sometimes it's better to be lucky that good.