Years ago I used to reload bullets I dug out from an old military shooting range backstop. Many were still in good shape, only having rifling on them. Others were so damaged I melted them down and cast new bullets.
I still know where there are thousands of spent bullets in the ground. Then I also used lead lining from building insulation designed for noise suppression.
Then there is plumber’s lead and lead solder.
I've shot straight wheel weight cast bullets from a .41mag with little to no leading problems.
Wheel weights too. I still have a big can of them from when I worked at gas stations in high school.
Pure lead "smears" and solder has tin in it to promote adhesion of the solder to other metals (it "wets" the surface). However some tin is desirable in a bullet alloy, just avoid using solder as the only alloy in your bullets.
You can add antimony to lead and increase its hardness which will prevent undo smearing. The good news is that wheel weights (used to balance auto/truck tires) are an alloy of lead and antimony and are usually replaced with new when re-balancing your tires. The result is garages tend to wind up with bucket loads of them which aren't easy to get rid of because of the toxic lead. Look around and you'll probably find someone who will give you all you'll ever need.
You'll need to melt the wheel weights down in a cast iron pot to separate the alloy from the steel mounting clips which sink to the bottom. Before pouring off the alloy, skim off the dross which is the crud floating on the molten alloy, then pour the alloy into an ingot mold. You can make a mold from a short piece of angle iron with flat steel caps welded on the open ends of the angle iron. The end caps should be long enough to act as feet to hold the mold facing upward.
You should check reloading manuals for a good bullet alloy recipe. The basic ingredients being pure lead, wheel weights, and soft bar solider (typically 60/40 lead to tin ratio). The manual should give you information on the percentage of antimony to lead in the weights so you can calculate the proper amount of the ingot you made to add to the pure lead and bar solder to make bullet casting alloy.
Regards,
GtG