How does zinc effect boolit

[Nora]

Been trolling the posts on zinc and contaminated lead. Was wondering what kind of effect it actually gives to the boolits? Lets say you've got some straight ww boolits cast from a .308" 150grn mold, and that is what the are as cast, .308/150. Now take the same mold and cast with zinc contaminated ww. All else being the same, would that throw the boolit at the same or different diameter / weight?

Nora

[44man]

It will be lighter. Zinc will not allow the boolit to fill out and it will look like a galvanized rain gutter.
If you put the lead in a pot and bring to 600* (Or a little less as long as the lead underneath is all melted.) and keep it there for a while, you can skim almost all of the zinc off the top. Do NOT flux or stir it, just skim.
You might lose a little good metal too but you can bring the lead back to useful.

[JohnH]

You won't get proper or complete fill outs. For lack of better wording, zinc keeps the melt from "shedding", it doesn't pour properly. In a way, it is like the difference between pouring water and syrup. Water pours. Syrup oozes. Same with zinc contamination. Boolits have surface voids. What I saw with the contaminated metal I had in the Lee 312-185 was a void consistantly in on the nose, and lack of fill out of the driving bands. One would almost think the melt was cold, in fact, I can well imagine a new caster thinking this was the problem, but no amount of heat will solve it. The only true solution is absolute prevention. No matter if you hand sort the weights, or simply keep the melt temp under 700 dF so that the zinc never melts in the first place matters not, but it must be kept out of the melt. I tried the heat reduction method to remove the zinc, but even after 2 hours of pulling dross of the melt I was never satisfied that I had it all. That batch became a weight for my neighbors tractor.

[DLCTEX]

No more than 2% zinc will alloy with lead, the rest will separate and will give casting problems. The zinc is lighter than lead and wants to rise to the top, so can be a bigger problem for a ladle caster than a bottom pour caster. Good boolits can be cast with contaminated alloy, but usually requires more heat. Frosting will not show as much with zinc contaminated alloy as it will with the regular alloys we use. The weight difference with 2% zinc boolits will be minor. A couple zinc WW in a large batch of alloy will not be catastropic, but a large number wiil cause you some grief.

[fastgun]

I agree with Dale. A little more heat from my Lee bottom pour has been the cure to using up zinc contaminated alloy for pistol bullets. I sure would not throw away any alloy that has some zinc in it.

[Bret4207]

If you take a knife and slice the long way on a heavily Zinc contaminated boolit you can sort of feel and see the Zinc. It's has a different appearance and feel than lead alloy, no matter how hard the lead alloy.

[44man]

If you want to have fun, try casting boolits or balls from pure lead that has some zinc in it! :bigsmyl2: Somehow a bunch of my ingots wound up that way, you can see the galvanized junk on the ingots.
Thankfully it is easier to get most of it out of pure lead, just skim everything off the surface when just melted. It is funny looking crystalized stuff.
Anyway it works and I can make good balls again without tossing the batch.

[dakotashooter2]

Some interesting comments. Most of the information you read indicates that any zinc even a minor amount, will absoulutely "ruin" the whole batch.

Has anybody tried swagging zinc? I would think a more acceptible bullet might be achieved by that method. I realize it would be more brittle but would think it might make an acceptible target or plinking projectile.

[DLCTEX]

I think the pressure required to swage zinc would be too great. Try to cut a zinc weight with a pair of wire cutters. It would probably require centrifugal casting to get good bullets with zinc, and much higher temps. You don't want to breathe the fumes from really hot zinc. I worked as a welder when I was much younger and welded galvanized metal on one large job. The boss just told us to drink lots of milk to get it out of our system. I doubt OSHA would let it happen that way today.