A couple of ideas:
Scrap dealers for sheet lead. They often have a pile of lead laying around and sell it for the going rate.
Stained glass shops often have scraps of lead that they have to haul off to get rid of. They generally have a bucket of it laying around. You might have to separate the solder from the lead edging they trim off.
Roofers sometimes find lead flashing. Electrical workers often come across lead sheathing for underground cables.
Xray techinicians that install new digital xrays end up scrapping old xray machines. Lead blocks are used for ballast for the moveable tables.
Sailboat repair businesses may come across lead ballast that is used in the keels of sailboats.
Below is an old email I've sent out alot to test the hardness of various lead alloys. It's good info:
To lead scroungers everywhere,
I think I got this info off the black powder or mlml list 8-10 years ago. I
would like to thank whoever originally posted it and offer my apology for
losing the original credits.
You can go to an art supply store and get a set or select individual pencils
whose core varies from [softest] 9B,>>>1B, HB, F, 1H, >>>9H[hardest]. Lead will run about 4B or 5B, depending on purity, and linotype will run about HB, or F. The hardest pencils will test aluminum alloys and are too hard for
lead. About 6 to 8 pencils will cover the range needed for informal casting.
To use, shave the wood away to expose the "lead" core without cutting into it
with the knife exposing 1/8-1/4". Hold the pencil vertical and sand the end
flat on fine (about) 400 grit sandpaper. Hold the pencil in a normal writing
position, and try to push the lower edge into the lead surface. If the
graphite core is harder than the alloy, it will cut into the metal or at
least seriously scratch it. If the metal is as hard or harder than the
graphite core, it will not be able to gouge. The hardness is ranked as the
hardest graphite core that will NOT cut in. If your bullet is resistant to
pencils from 6B through 2B, but B scratches it or peels up a small shaving,
the hardness is 2B.
This isn't as exact as a Brinnel tester but cost effective enough for me. You
can reproduce your hardness but not necessarily the same cost, or castability
but all I want to know is whether it is REAL HARD, sorta hard, somewhere in
between, soft, and REAL SOFT (i.e. Smokeless rifle lead, smokeless pistol, 38
special lead, and 2 grades of black powder lead). I bought 8 pencils: H, HB,
B, 2B, 3B, 4B, 5B, & 6B. I found that my various ingots of lead were not
sorted so well once I pencil tested them. Wheelweights and MY BLEND of #2
alloy are about 2B and my soft cap&ball lead is 4B&5B. Be sure to use a fresh
surface as some of the heavier grey corrosion will resist the pencil core but
the underlying lead will scratch.
Note: get all the pencils from the same manufacturer as some are varying in hardness between brands.
With over 15 perCUSSIN' revolvers, I've been called the Imelda Marcos of cap & ball.
SASS#3302 (Life), SASS Regulator, NRA (Life), DGB#129
Wolverton Mtn. Peacekeepers (WA), former Orygun Cowboy (Ranger, Posse from Hell)