Adding tin/pewter to lead, why?

[JeepsAndGuns]

Still new to casting, but I am learning a lot.
I have seen lots of threads and posts over my time of searching the last few weeks (here and other sites) where people are searching for pewter (or tin) to add to their lead for casting. I had to look up pewter as I had heard of it but knew nothing about it. Found out it is mainly tin, hence the reason casters seek it out as a slightly cheaper source of tin as opposed to buying straight tin. Ok, so now I know what it is, but still can not figure out why I would want to add it to my lead.
In all my reading, all I can find is "for better mold fill out". That is about as much info I can find on as to why it is added.

So far all I have cast is shotgun slugs. I also have a 00 buckshot mold but have not used it yet as I found about 20 pounds online. So once I shoot that up, I will start casting it. But as of now, just slugs. I do not have any plans on pistol or rifle bullets, as I have a large supply of copper jacketed bullets.
So far I do not seem to have any issues with the molds filling. Or, at least not that I know of. They seem to take the shape of the mold fine, at least to my eyes? Only time I have issues is when I cast my first 2-3 slugs before the mold is fully warmed up. I pre heat the mold some with a propane torch before I start. The first few will not cast right because the mold is still to cold, so I toss those back in the pot. But after that, I seem to have no problems.

So can anyone explain the reasoning behind adding it to the lead in a little more detail, or perhaps have any pictures of bullets with and without tin, showing the difference?
Just trying to learn and not having much luck searching (or just not searching the right terms?)

[Winger Ed.]

It increases the fill out, and makes the alloy harder.

You'll notice the better fill out with molds that have more and sharper detail than others.

[Kosh75287]

I don't think you'll get to this point, but when a great deal of tin is added to lead, it becomes more difficult to obtain a homogeneous alloy. To keep the tin/lead mix from "layering out" before/during casting, a bit of antimony (0.5 to 2.0 weight %) can be added to, in effect, make tin & lead "more soluble" in each other.

[Dusty Bannister]

I don't think you'll get to this point, but when a great deal of tin is added to lead, it becomes more difficult to obtain a homogeneous alloy. To keep the tin/lead mix from "layering out" before/during casting, a bit of antimony (0.5 to 2.0 weight %) can be added to, in effect, make tin & lead "more soluble" in each other.

On the LASC site it describes the vertical currents within a melt but not gravity separation. Any idea where I could read about "layering out" of tin after it is in solution with lead?

[kungfustyle]

Surface tension, adding tin reduces the surface tension of lead. If you drop water on a table it pools or beads, yes? Surface tension. The lead wants to turn into a ball, that's why you are able to get a shotgun slug or black powder round balls fairly easily. All the nooks and cranny's get filled into a mold when you add tin.

[mfraser264]

2-3% tin is a good mix for most alloys we use. Tin in Lead is a grain refiner, creates smaller and more uniform size grain when solidifying allowing for smaller details to fill out. Tin does harden Lead a bit but only a couple of points. After a given percentage, Tin will not increase hardness, need to check my notes to recall how much.

[GhostHawk]

Tin does add some hardness, but Antimony is much more efficient.

I like 1 to 2% tin as I get nice shiny bullets, and good fill in my mold as long as the melt and mold are warm enough.

My normal alloy is roughly half COWW half softer range scrap, plumbers ingots, or lead pipe. Whatever is soft, cheap, and available. To that I will add 1% of high tin pewter, or Lino. I have a little lino left, mostly try to save it for rifle.

Pistols with their generally below 1000 fps are not as fussy.

But that is just my preference.

And I have some pewter cast into rifle boolits for adding just a touch more to a batch for rifle or higher speed application.

[358429]

Tin adds strength and helps the metal flow to capture fine details in the mold. Adding

antimony in a matched ratio with tin greatly increases strength and makes

casting fine detailed boolits easier.

When you cast if you dump early because its easy to drop the bullets from the mold

they smear bases, dent or crack-defect because they are still soft.

If you dump late to allow them to solidify more, they stick to the mold and hollow

point pins because the mold and pins are now too cold.

I like https://uploads.tapatalk-cdn.com/20211210/04cdf215d510c9183b59528f8b1360cf.jpgpretty bullets. I am loading these with H110 to feed a snub nose 357 magnum.

In fact I assembled the ammunition and filled the https://uploads.tapatalk-cdn.com/20211210/9acd4efc7f02422601b9f8ebe8f0ebe2.jpgspeed loaders an hour ago.

[William Yanda]

For shotgun slugs pure lead is desirable. Besides its hardening effect, added tin also lowers the melting point. Antimony will harden more with less added. Buckshot may benefit from being harder, less deformation leading to fewer stray pellets. Hardness really comes into play with higher velocity projectiles from rifles and a little less so for pistols.

[Cosmic_Charlie]

You may want to harden those 00 buck balls a bit. But coww alloy would be the way to go for that. There are some vendors here on the forum that sell coww ingots and that would be an easy way to try it.

[JeepsAndGuns]

Does anyone have any pictures of bullets cast before adding tin, and then cast after adding tin?

I guess there must be some odd shaped molds out there that are hard to fill? I guess the molds I have must be pretty simple. I have a lee key drive mold and a russian made copy of the lyman sabot slug. Both seem to have no issues filling.

[bangerjim]

I use 1-2% Sn in everything I cast to lower surface tension and get the nice details of the molds. As said, it adds very little to the hardness. That is Sb's job. But casting without it is mainly a BP roundball scenario with soft lead.

You will find your boolits are more consistent in shape, size, and detail with 1-2% Sn in the soup.

If your 2 molds ( I have 60+ 4/5/6 cavity molds) do not have any problems with fill and detail, don't sweat the Sn addition. I just find the Sn eliminates one of the several potential problems with casting any shape and size.

[Bazoo]

In simple terms, adding tin makes an alloy cast easier. You can cast without tin. But it’s a frustrating casting session with a resultant larger amount of rejects due to incompletely fillout. For me it’s the difference between 60% keepers and 90%+ keepers.

Tin adds ductility. It means you get bullets that deform instead of fragment.

[JonB_in_Glencoe]

SNIP>>>

So can anyone explain the reasoning behind adding it to the lead in a little more detail, or perhaps have any pictures of bullets with and without tin, showing the difference?
Just trying to learn and not having much luck searching (or just not searching the right terms?)
read the third Chapter: Alloy Selection and Metallurgy

http://www.lasc.us/Fryxell_Book_Chapter_3_alloySelectionMetallurgy.ht m

[JeepsAndGuns]

Yesterday was a rainy day, so me and the significant other hit some thrift stores, pawn shop, and a antique store/flea market.
The antique/flea market was the only place that had anything pewter and it was all over priced.
There was also a lot of stuff tagged as pewter that was actually not (aluminum and that alloy of aluminum I can not remember the name of). Seems around here, pewter has more value as the items.
I think I would be better off just buying new fresh tin.

[bangerjim]

Yesterday was a rainy day, so me and the significant other hit some thrift stores, pawn shop, and a antique store/flea market.
The antique/flea market was the only place that had anything pewter and it was all over priced.
There was also a lot of stuff tagged as pewter that was actually not (aluminum and that alloy of aluminum I can not remember the name of). Seems around here, pewter has more value as the items.
I think I would be better off just buying new fresh tin.

I found that total lack of peter years ago here in AZ. I quit even trying for pewter tankards. plates, and food service-ware like a few on here brag about finding and melting down. Most pewter items I find are valuable antiques and go into my wife's ever-growing collection.

Watch out for those dreaded aluminum "Bread of Life" plates that pop up everywhere! The untrained eye will think they are of real pewter metal.

Keep an eye out in the S&S section on here. There are those that sell pewter every so often. And there is always Rotometals for pure Sn, my choice above pewter.

[William Yanda]

Watch out for those dreaded aluminum "Bread of Life" plates that pop up everywhere!

And the Kodak 100 years....or is that only because I live an hour south of Rochester, NY?

[quack1]

Does anyone have any pictures of bullets cast before adding tin, and then cast after adding tin?

I guess there must be some odd shaped molds out there that are hard to fill? I guess the molds I have must be pretty simple. I have a lee key drive mold and a russian made copy of the lyman sabot slug. Both seem to have no issues filling.

Here is a picture of bullets from a lightly pitted wadcutter mold. Bottom row are bullets cast from straight COW. Top row are cast from COW with about 2% tin. The tin reduces the surface tension enough to allow the alloy to flow into the pits.
https://i.imgur.com/ntzBuBPl.jpg

[kevin c]

Quack1, how are the edges of the lube and crimp grooves on the straight COWW bullets? Were they filled out properly? It’d be ironic if less fill out produced a better looking and still functional bullet.

[quack1]

Kevin- The lube and crimp grooves look pretty good, just a few pits showing. The bullets are probably more accurate than I am with a pistol. They drop from the mold at a little over .358 and it happens that my model 19 shoots best with .357 bullets. After sizing to .357, the bands of the bullet don't have any visible pits. I don't currently have any that aren't sized and lubed or I'd include a picture. Not bad for a $5 DC Lyman mold found at a flea market.