Does zinked alloy cast small for you?

[Rick]

No, that chart is from Lyman, RCBS, Hand Loader and others. I am also saying that it is in reference to antimony NOT tin. I am also saying that the values are approximate and for a suggestion as to what to expect . . . From antimony. The question here regards tin. Review the matter!

 

[Rick]

The problem with charts is they are only valid for the person who made them. Variances in equipment, ambient conditions, component temperatures, and individual technique can make bit of difference in the way things turn out.

Rick generates his own data, which is why I was pretty much floored by what he wrote. But he got the results he got, for some reason.

What is on my web site is about the effect of antimony on size. What I wrote in the thread is from my measurements of my bullets. Pretty simple I think.
.

 

[AMTom]

As I said, multiple folks repeating myths. Redding/Saeco states that tin has no effect at all.

They are wrong.

The question here is about tin, not antimony. I am answering the question because I know the answer. I know the answer because of scientific testing. Not because I get my "knowledge" from copying "facts" from someone else.

 

[Ian]

My question was if a small (not catastrophic) amount of zink is present in a clip-on WW alloy, would that explain why adding tin THIS TIME had absolutely no effect on as-cast diameter?

I wanted bigger bullets, added some tin, got no joy, am confused because this doesn't match the results I remember getting consistently in the past.

 

[JWFilips]

Gee Ian,
Don't you clip test every piece that goes into the smelting pot? I do..........
Jim

 

[popper]

I've cast Pb/Sn (too much) & Pb/Zn. at low Zn content. they come out small.

 

[Ian]

I lapped the mould tonight and got it where I needed it with this alloy, so problem solved. The bullets I cast two days ago had grown exactly zero inches. Pretty sure Popper and Fiver are right about light zinc contamination making the bullets just a titch small.

 

[fiver]

I know popper uses zinc sometimes even if it's just for trading out for copper.
but even using it for that will leave trace amounts and you can see it's affects.

you might have just got into a smaller part of your bigger batch that has more than most of the rest.
small amounts on non sbsn stuff make a difference and our problem is we deal in .001's an insignificant measurement to most of the world.
but super relevant in ours.

IMO tin doesn't promote diameter growth it does provide better fill out of available mold size.
but once it's there it's there.
tin doesn't migrate like antimony does to form fairly even crystal distribution.
it stays where it cools and that's mostly near the surface.

in my mind that explains why tin is a retarder in final BHN when an alloy is water quenched.
and why it's possible for it to tear off the sbsn chain when more is present than there is antimony available to bind with.
and why it ends up on the surface of the boolit surrounding spots of soft non alloyed lead.

the zinc being present sucked up some of the tin [as much as possible tin is super attracted to zinc] not allowing it to act as a flow [wetting] agent to let the alloy break through to the surface and gain the extra diameter.

alloys act a lot different than is normally predictable depending on how much of what is in them.
nothing is linear when you start adding in stuff and especially stuff that reacts strongly with the normal players in the game.

 

[Rick]

Well said Fiver. ^^^^^^^^

 

[Reed]

Not any oatmeal except the normal oxide scum from throwing sprues back in the pot. Problem with this batch has always been flow, the alloy won't fill even Lee's microbands very well unless up over 725 pot temp and running the mould about as hot as can be run without quenching the sprue on a damp sponge (been using the fan on sprues). I'll see if these don't grow some over time, IIRC this alloy usually does that if I don't size them right away.

Dusty, after adding tin the tendency for a fractured crystal pattern reduced to a lightly porous mess (sprue hole too small to flush out oxides from the pour), so yes, without tin the metal acts as you describe. If I cut the sprue too soon it makes a goat-arse pucker like the inside of a crystal geode. I'm going to cast the rest of this alloy out with a different mould and try a different metal with these bullets.

You have just described the first five years of my casting experience. I got a screaming buy on several hundred pounds of new clip on WW, and have never cast a decent bullet with it without running the pot so hot I wonder if the sprues are ever going to harden. Clogs up the sprue hole, casts small, everything you've said. Since I didn't have any experience with casting at the time, I naively thought that was normal. I hadn't even heard of zinc in WWs back then. But your suspicions of slight zinc contamination reinforce a nagging thought I've had about this lead for a long time. That batch is about gone now, and life is good at the pot. But I'm sorry to know that you are in that spot.

 

[Ian]

No big deal, Reed, I normally use this alloy for bullets I want on the smaller side, or when it doesn't matter. It works great for .45 ACP (still need about 150 lbs of those to finish loading all my brass) and stuff that needs powder coating. The fact that adding tin didn't have the normal fattening effect just left a big question mark in my mind. Starting out a casting career using such a disagreeable and mysteriously-behaving metal must have been beyond frustrating for you. I usually recommend a new caster begin with some certified alloy so they know what to expect.

Since I'm casting 500-grain bullets for a semi-auto rifle, the consumption is likely to get a little out of hand, and since I'm powder-coating them, I wanted them to cast a little small. Unfortunately between a little out of round and a little too small on the bands I was in a bit of a pickle, but lapping the mould fixed both issues entirely and I didn't have to resort to using better alloy for bullets that make 14 per pound and will probably get consumed like Skittles.

 

[JonB]

I did a amateur experiment "Zinc in small percentage in bullet alloy" which was exploring hardness and such, see post #6 for test details.
http://www.artfulbullet.com/index.php?threads/zinc-in-small-percentage-in-bullet-alloy.589/

using 1% Zinc in 94-3-3, I didn't see any size differences between the control alloy and the 1% Zinc added alloy...same with the weight, the control alloy and the 1% Zinc added alloy weighted the same. I don't recal how many samples I used, but since it wasn't a major portion of the experiment, I've suspect I measured and weighted five of each...which is my usually for weighing and measuring a batch of cast bullets, I do that for every batch I cast.

 

[Ian]

Maybe I have more zink than that? I know there's less tin, and probably some calcium still.

 

[JonB]

Well, I don't know?
But like Fiver said, "alloys act a lot different than is normally predictable depending on how much of what is in them."
My alloy had a balance of Sb and Sn...whereas your WW alloy had little tin.
I could go on, but I'd only be speculating...and I don't have enough metallurgy knowledge to do that.

 

[popper]

You need to look at the size of the atoms or molecules of the various components of the alloy to see if it grows or shrinks in size. Same with weight. Some components just pool or dendrite, others actually form a different molecule and have different characteristics. I've been playing with a Pb/Zn/Cu alloy to see if I can use Zn vs Sb for a good harder alloy. So far just leading & tumbling in 40SW but ass a touch of Sn and its good in 40 & 30/30. Got to ssend it to get XRF so I have a baseline to dicker around with.

 

[fiver]

let us know Popper.
I just got some more zinc ingots to mess around with.
I was just gonna add 1% to some ww/soft alloy and play with it and heat harden the alloy to see what I get.

 

[popper]

Had a terrible time with tumbling in the 40, beagles the mould didn't help. Thought it was the case sizing the base. Duh, I was using the 401 sizer, not the one I honed out for softer PB/Sn alloy. 401 sizer is 401 boolits, right? Cast a couple doe zen more to try again. Using BLL so I get alloy only results. And need to test the Honady half jacket in the AR BO. Pistol.