I picked up some lead flashing from my local metal recycler last year.
A couple years before that, I got one of those vinyl coated, mushroom shaped, lead boat anchors from them. I haven't melted either one yet. I also have bought printer's type from them. Got a coffee can full.
I used to be able to get lead battery bars (from electric forklift batteries) from the battery companies at work.
They are the intercell connector bars that are on top of the battery cells. Each cell has 2 or more posts that come out the top of the cell cases. The bars are welded to the posts with 50/50 solder or recycled bars, and connect the cells electrically.
Bullets I've cast from them are a little bit harder than those cast from wheelweights (my other favorite bullet alloy).
I need to build another furnace so I can get back to melting aluminum, zinc, and lead.
I have a fair bit of lead that needs to be cast into ingots.