High Copper Alloys- Lets discuss this further

[badgeredd]

That won't be a WAG, Edd, if all individual elements are "married" as a single unit. Zero slush stage? ... felix

Unfortunately, in my case, it is a WAG, BUT what you are saying makes perfect sense to me.

[303Guy]

I finally tested copper only as the 'hardening' agent. I started out with lead pipe and added some perter for the tin (Super Fine Pewter to be exact). I assume it to contain 6% antimony and 1.5% copper. I dissolved possibly enough copper to bring the copper content up to 0.3% - maybe less. Antimony should be 0.24% and tin 3.6%. This drops from the mold quite hard enough for I needs I think. About the same hardness as 50/50 COWW/lead. It seems to have softened overnight though. What I have learned is I need a harness tester! And a toughness tester. The next test is to fire a few boolits into medium to test for expansion.

[felix]

Raise the antimony! Stuff should not SOFTEN that FAST! Shooting might roll down some tin muck which could be a lot harder to eradicate out of the barrel. ... felix

[runfiverun]

you still need a fairly balanced alloy.
i don't think the high tin content is gonna work right either.
i'd look to get the antimony up there to the 3% mark.

i know you don't have a lot of alloys to work with,but sometimes you just gotta break out the checkbook to find stuff out.

[madsenshooter]

My babbit, which has 10% Sn, doesn't soften, but it has way too much Sb.

[303Guy]

I rechecked and the hardness hasn't changed from when first cast. This morning I did a hammer test comparison with 50/50 COWW/lead. The two alloys are quite similar, with both resisting the first blow about equal. Further blows did flatten the alloy a bit more than the 50/50. I've just had another look at the residue of the copper I was dissolving and it seems I got way more in than I thought, possibly as much as 80%. I'll use 75% as an estimate - that raises the copper to nearly 0.4%.

Tin smear of the bore is not an issue as these will be paper patched. Since the 50/50 alloy is not brittle and I can find some COWW (I'll start collecting tomorrow) I'll use that for plan cast. At this point I haven't seen any detrimental effect of high tin - not that 3.6% is high, after all 20:1, 30:1 and 40:1 lead-tin used to be the standard alloy for plain cast, admittedly, often used with a cloth patch for round ball. I'll try a 2.5% tin alloy next time round with as much copper as the mix will absorb and see what happens. Now to go fire some boolits to see how the expand in rubber grinds.

[303Guy]

Right. So I cast a few boolits and loaded one up and fired it into the test tube. Powder charge; W780 - 43gr Boolit weight; 200gr patched. Recovered boolit weight; 187gr (94% weight retention). Expansion pretty darn good at 0.7 inch (18mm). Penetration into the rubber grounds not too fantastic, about a foot (300mm). Primer flattening indicates good pressure - more than a moderate load but not absolute max either. I won't go any higher.

So it seems the alloy is not too bad for hunting. The boolit base is intact and a short bit shows the rifling nice and sharp, almost as though there was no paper patch.

To answer the suggestions made, like increasing Sb, the whole idea of the exercise was to achieve boolit toughness without Sb. The tin content was a little lower than I was aiming at - the pewter tumbler was thinner than I thought - but I left at that thinking that pewter is rather expensive actually (well, it's an effort to get the stuff).

On the apparent softening of the boolits - I don't know what happened there. The sample did seem to be softer this morning (that one got the hammer test) but the other samples didn't seen so soft. I couldn't push a test casting through my push through sizer but last light one went through with some difficulty. I cast two small lots this evening, the first pretty hot (had to raise the melt temp to get the silver shiny, flaky stuff melted in) then the second batch a bit cooler. The cooler ones came out the mold harder!

Oh, this alloy doesn't cast well by the way. I think I've got too much copper and not enough tin. Anyway, I'll play around with it and see what happens.

[badgeredd]

check

[olaf455]

Have you fired any of these yet?
What caliber/s are you testing?

[badgeredd]

iiiiiii

[303Guy]

First some more on what appeared to be an overnight softening of the alloy - it did it again with a new casting. Fairly hard as cast, quite a bit softer overnight, but - it has hardened again during the day! About as hard as COWW.

The cast-ability alone makes me wonder about this one. In my mold there is a tendency for the boolit to shrink about a quarter way up, forming a wasp waist with hot melt and wrinkles with a cooler melt. A conventional aluminium mold leaves rounded edges and some wrinkles on the nose but casts shiny. Then there is that silver flaky stuff that forms on top at lower temp. What could it be - inter-metallics? It melts in at higher temperature and at lower temperature it returns to the surface with stirring. Would a 'balanced' copper alloy resolve the problem? Or is it simply too much copper and not enough antimony? What does more tin do to the alloy (for paper patch)?

With what's in my pot now I could go one of two routes - add more lead or add more tin. I'd like to see what more tin will do out of curiosity. I'll drain off a few ingots for adding more tin later and add lead to the rest and see what I get.

[olaf455]

In layman terms please...lol...

[303Guy]

Thanks popper. I'll have to re-read that after taking a couple of asprin and a few medicinal beverages.

I fired up the pot again yesterday afternoon, choosing a power setting between the two I've used before. It was enough to absorb those flaky bits. I tried a different mold and found the castings to be about perfect and the released from the mold easily, unlike the previous ones. The hardness as cast is the same as now (overnight). I only stopped casting because the pouring spout blocked up!

It appears that an extended times between casting and loading won't be necessary with this alloy.

My alloy seems to fit that bill too. That's a great quality. Is it the copper that does it?

Ummm ..... as olaf455 puts is, can you say that in layman terms? Most of us out here are mere mortals and I think understanding that is good casting sense (knowing what is actually going on) for all of us.

[felix]

Copper when not remaining in solution migrates to the outside of a swirl during a drop from a spout. Copper freezes in "zero" time and gets thicker and thicker until the spout is frozen shut. Before casting, run a cup of alloy back and forth between two pots: If "sheeting" is seen, then you got the copper coming out of solution. The marriage of components DID NOT take place. ... felix

[303Guy]

Thanks, felix. That also explains some boolits with hard and soft zones - the stream was building up then collapsing in rings in the mold, leaving circumferential creases on the casting. Will raising the temperature open the spout?

[felix]

Yes, and continuous stirring. You are forcing a shotgun marriage to occur with this technique. See if the boolits shoot straight before making a major batch. Chances are they won't because of the eventual divorce within the boolits causing serious imbalances. Won't matter for close-in mean and tough targets. ... felix

[303Guy]

Thanks, felix. Ok, that was an experiment and for now there is no reason not to just blend it in with 50/50 for a working alloy.

It occures to me that I may have burned off much of the tin - there's a heap of yellow dust forming on the melt. Is that lead or tin or both?

[garym1a2]

Their is some high copper babbit for sell in the selling and swaping section.

[badgeredd]

Ymmv...........

[Jim Flinchbaugh]

Just dropping by, since I started this thread and kinda wondered off, I check everyday, read, copy & paste
just havent had much to add.
I checked the batch I made in late December today for size, only a .0002" difference in 2, and no change in 1, of the 3 samples.