Sticky lead problem

[PBaholic]

I picked up about 5lbs of unknown lead at the scrapyard. It was already BHN 10, so I melted it in my Lee 4-20 pot. It needed a higher temp to flow right, but the boolits really stick in the Lee .45 - 230 grain moulds big time. Normally my tops fall off when I cut the sprue, and a good wack gets them to drop out. These guys required a lot of wacking to get them out.

I added about 3 oz of tin to the mix, with no change. I added 2.5 lbs of my normal BHN 10 with no change. I ended up pouring out all the lead, and set it aside. Replaced the lead with fresh BHN 10 lead, and cast about 500 boolits with no problem.

I normally cast about 1000 boolits a month, and have been doing so for many years. I've had bad lead before, but this stuff mystifies me. I came to me in unmarked 1 lb ingots.

I re-tried a 2 lb batch again, with the same results. I added another 3 oz of tin, with no change. I heavily smoked the mould with no change. I increased my casting temp from 700 to 800, with no change.

I have had zinc contaminated lead before, and it was kind of stringy, but this stuff is not like that. I add about 1 lb of it to 7 lbs of my regular lead, and it seemed OK, but 2 lbs in 7 soured the whole mix.

What is this stuff?

[Dusty Bannister]

Weight comparison with the two cast bullets. So both alloys are 10 BHN, but how old was the problem batch when you tested it? What is the appearance of the bullet bases and sprue cuts. Smooth or ragged? Crystal formation on bullet base? First comparison would be weight and measurement of as cast diameters.

[Bzcraig]

Could your unknown ingots have been solder? I would think high tin content might hold on to a mold pretty tight.

[scottfire1957]

What is this stuff?

How in the world could we know? Anything posted here would be at best, a guess. YOU need an analysis.

[runfiverun]

it could have anything in it.
the weight would be a clue but calcium or indium might not show up on an analysis.
I'd just mix a small amount into a bigger batch and run with it.
or just toss it out your only talking about a few lbs.

[243winxb]

More heat will cause more shrinking of the bullet.. Try maximum heat in pot and mould.. You want frosted bullets as they drop from the mold.

[OS OK]

I had recently a problem with the sprue sticking to the plate in an old Ideal single gang HP mold...was whacking too much...I took a q-tip and lightly applied some 'anti-seize' to the top of the sprue plate and that stopped the whacking.
However...I have no idea what it would do in the cavities.
It was applied as thin as I could smear it.

[PBaholic]

Weight comparison with the two cast bullets. So both alloys are 10 BHN, but how old was the problem batch when you tested it? What is the appearance of the bullet bases and sprue cuts. Smooth or ragged? Crystal formation on bullet base? First comparison would be weight and measurement of as cast diameters.


You nailed it!

They are not shrinking. I hadn't sized these, as I normally powder coat them first, but I sized both the sticky and regular boolits. The sticky ones were much bigger than my regular ones by .001". My regular boolits don't really need to be sized, but I do after I powder coat them to break off the excess powder coat that puddles at the bottom.

The sticky boolits are light too, only weighing 220 grains. Normally my 230 grain boolits come out a little heavy at 235 grains, because I'm using a higher lead content at BHN 10.

I recast all my lead into a 2.5 lb ingot for storage. These fit and stack well in the 2x4 wall space of the shed where I pour. The sticky lead measured BHN 10 after 24 hours, and again a few days later. I did the acid test on them today, and got no fizzing.

As I compare these boolits, the sticky ones are very smooth, but frosty, like aluminum. My lead boolits are usually frosty anyways, but these sticky ones have a much finer crystaline structure. The sprue cut looks similar with a slight crystaline formation in the center. These didn't feel any tougher than my normal lead when I cut them. The base of the boolit is smoother, with a finer crystaline structure, again almost like aluminum.

I did have to raise the temp to get them to flow right out of the pot. I can cast my normal lead all the way down to 500 degrees before there isn't enough heat to keep it flowing right. The sticky lead won't flow until it was well over 700 degrees.

I guess I'll just keep this stuff for a project where I don't want any shrinkage.

[PBaholic]

Could your unknown ingots have been solder? I would think high tin content might hold on to a mold pretty tight.

I have some solder bars, but I've never tried to cast with them. 50/50 solder is BHN 14, and 60/40 solder is BHN 16, and this stuff is much softer than that at BHN 10.

I think it's something other than tin and antimony. Probably cadmium or bismuth.

[PBaholic]

What is this stuff?

How in the world could we know? Anything posted here would be at best, a guess. YOU need an analysis.

Yah, I know that :)

I've had good luck by just mixing to the right BHN. This is the first time my method has failed me.

I had an opportunity to get an XRF gun recently too. My local county was selling one off in an on-line auction, and opening bid was $150. It had just been resourced 2 years prior, so that would have been a spectacular deal. What was scarring everyone off was they required you to have a radiation license to buy it.

15 minutes before the auction was to end, it was still sitting at $150. I bid it up to $2k, but whomever had put in the initial bid, must have known what it was really worth, and put in a significant high bid. I let it go, as that would have really put a cramp on my boolit budget!!

[243winxb]

A high % of antimony makes bullets bigger and lighter. Also requires more heat.
Bullet Sizes & Weights – How to Vary Them
The bullet diameters and weights presented in this list are based on the use of Taracorp’s Lawrence Magnum bullet alloy (2% tin, 6% antimony, 1/4% arsenic, 91.75% lead).

Bullet diameters and weights will vary considerably depending on the lead casting alloy used. This variation can be as much as 1/2% on the diameter, and 8% on the weight among the most commonly used casting alloys. For example, a .358-158 grain bullet might show a diameter variation of .002", and a 13 grain difference in weight.

Of the most commonly used alloys, wheel weights (.5% tin, 4% antimony, 95% lead) will produce bullets having the smallest diameter and heaviest weight, with such bullets running approximately 1/3% smaller in diameter and 3% heavier than bullets cast with Taracorp's metal. Linotype will produce bullets with the largest diameter and lightest weights. This alloy will produce bullets approximately 1/10% larger and 3% lighter than Taracorp. Other alloys of tin and antimony, with antimony content above 5%, will produce bullets with diameters and weights falling between those cast f rom wheel weights and linotype.

Alloys containing little or no antimony will cast considerably smaller than wheel weights and in some cases will produce bullets too small for adequate sizing.

Within the limitations given above, the weight and diameter of a cast bullet can be adjusted by varying the
alloy’s antimony content.

The size and weight of bullets of a given alloy will also vary according to casting temperature. Higher temperatures will result in greater shrinkage as the bullet cools, thereby producing a slightly smaller and lighter bullet than one cast of the same alloy at a lower temperature.
http://www.redding-reloading.com/online-catalog/88-bullet-moulds-charts