1 Attachment(s)
Broke one - and repaired it
Based on my own experience:
1) The best source of pure-enough lead is lead flashing as used by roofers. It has to be pretty pure to be sufficiently malleable.
2) You do not need 99.99% chemically pure lead, that is just wasting money.
3) But you should avoid wheel weights and any other supposedly favourable source of scrap recommended by someone at the bar who knows about as much about metallurgy as I do about Sanskrit. As you have found out, the hard way, it only takes tiny amounts of some impurities to ruin the alloy.
4) Repeat: stick to lead flashing.
5) So-called "fluxing" can only have an effect (if any) on the top of the melt, where it may indeed reduce oxidation. But anyone who thinks that all the various snake-oils that are proposed as flux actually penetrate into the melt and mix with the alloy should think again. If a steel mould floats on molten lead, be sure that beeswax, earwax, whatever... cannot do anything else but also float on top.
6) For BP applications, hardening with tin is all you need. And the simplest way of acquiring tin is in the form of good-old eutectic solder as used for electronics work. 5% tin provides a BH of about 10. It's not critical, so I avoid brain strain and add 8% solder by weight (which I can calculate in my head) to the lead, for BPCRs, or 5% solder (approx. 3% tin, or BH 8) for percussion rifles, such as the Gibbs. Pure lead is, by definition, BH 5.
And finally, from the "been there, done that" department:
I, too, have managed to break a (Lyman?) mould handle, about a year ago. And under sheer desperate time pressure, silver-soldered the pieces together.
The material seems to be a kind of brittle steel, but not pure cast iron (thank heavens).
Attachment 42444
Not pretty, but it is still working after a year. Try it - you have nothing to lose!
