I thought this subject had been discussed before, but could not find it. Just thought I would offer what seems like a way to make short work of cutting lead. I do not know if it is an original thought.
Put a wood blade with big teeth - can be an old blade - in a reciprocating saw, hold the lead in a vise and slice away. Use eye protection, of course. It will vibrate like a son of a gun, but it goes pretty fast. I used a high quality (white color) blade and that blade probably will have a longer life than a cheap one, but it seems like the size of the teeth is what matters. Should be able to make a lot of cuts using the same blade.
It is a joy to make fast cuts, though I stop and recover often when my unhappy arms tell me they have vibrated enough for a while. The good thing is it cuts nicely rather than making a lot of heat and binding like with a metal cutting blade.
Scott