You may have already done this but check with some scrap dealers - see if they have any lead from lead sheathed cable - I used to be able to get it and it was great stuff. I had about 200 lbs. of it and it got stolen out of my shop building - I know who did it but can't prove it. If he'd come back, I'd be more than happy to send some more lead his way.
Also, try checking with some large plumbers who do commercial work - especially in older buildings. Often times, they collect and separate the various fittings and pipe and then sell it for scrap. If they happen to run in to buildings with old leaded joints on cast iron soil pipe - that is usually pretty good stuff as well.
If a pair of '51 Navies were good enough for Billy Hickok, then a single Navy on my right hip is good enough for me . . . besides . . . I'm probably only half as good as he was anyways. Hiram's Rangers Badge #63