Alloy Quizeler!

[Rick]

I too have done a huge amount of alloy testing, I learned a lot from it so it wasn't a waste of time. I had a whole wall of the shop lined with many different piles of ingots all marked with what they contained, it got out of control quickly. The biggest lesson I learned is that using as consistent an alloy as possible is a good thing but a specific alloy for a specific use isn't really all that important. The proof of that is easy to see, just look at the huge variety of about every alloy out there being used and a great many people getting excellent results with them.

I did learn that in long range revolver grouping using a consistent BHN is important, vary the BHN within a group and the groups open up significantly.

Anymore I try to keep it simple, I had 800 pounds of clip-on wheel weights and I blended them all together to form one consistent lot of 5 pound ingots. I had 500 pounds of stick-on weights and I blended them all into one uniform lot. Almost all of my shooting now is with air cooled CWW with 2% Sn including rifles to 2000 fps. For very top end high pressure revolver loads I heat treat the same alloy to 18 BHN. For low pressure/velocity and HP bullets I use the stick-on weights with 2% Sn, air cooled of course because without the Sb it wouldn't heat treat.

Should i need or desire to experiment with alloys I have about 30 pounds of pure bar tin and a couple of ingots of Roto Metals Super hard. With the clip-on weights, the stick-on weights, the tin and the Super Hard I can make up most any alloy I might desire. I did experiment with the super hard and the stick-on weights, when wheel weights started to get hard to find I looked to see if I could duplicate the clip-on weights using stick-ons since the clip-on weights are far and away my most used. That is quite easy to do sans the arsenic. Since I do little heat treating anymore the As is a mute point but even heat treating to 18 BHN with the stick-on, Sn, Super Hard alloy no arsenic make no difference.

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[JWFilips]

Well I guess I mis-estimated the amounts of what was in that one big layered block of lead!. Must have not been as much hard alloy ( Isotope containers) as I estimated.
I did a water drop of about a dozen bullets Sunday and just tested them this morning and only gained 1 BHN higher( now 11) then the air cooled (10).
I know it is only 3 day of curing but I'm sure if it was what I estimated it should be harder by now.

My mix contained
28 lbs of commercial hard cast alloy
7 lbs of linotype
41 lbs of pure lead
4 lbs of COWW
1/4lb of tin
and what I thought was 10 lbs of Isotope cores

After 1 week it testes BHN 10
This mornings tests after water dropping ( 3 day ago) only reach bhn of 11 soI guess I really was off a lot
I was hoping for at least 15 bhn

 

[Rick]

Jim, the amount of quench hardening is directly related to the percentage of antimony. Use the alloy calculator to see how much Super Hard you need to bring up the antimony to 2-3%, shouldn't take much. At 3% Sb it will quench harden both more and quicker.

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[Brad]

How hot was the mould you dropped them from? Temp at quench also makes a difference. A heat treat to a known temp would give a slightly better answer.

Like Rick said, a little more Sb and all will be fine. Bet you will be surprised at how little super hard it will take.

 

[Ian]

I second Rick and Brad's comments above and will add "test the bullets every week for a full month". If you cast from a mould that's barely warm enough to not wrinkle, you won't get much quench hardness. A $40 convection oven and $3 oven thermometer from wall of china mart will do wonders for your heat-treated rifle bullets.

Even if your cores were soft and your linotype depleted that alloy should make 18 bhn or so in three or four weeks if quenched from a hot mould. Might make 20 at maximum oven heat treat. As far as I can tell, excess tin, like more than 1/2 the amount of antimony, can make the process of age hardening sluggish, however Rick has more experience and input on that than I do.

 

[JonB]

I have a pretty good sized batch of automotive battery terminal alloy (thanks to Ian). When I cast (air cooled), the first day they are quite soft, like 9.4BHN. a week later thay are 11, two weeks later 11 or maybe twelve, three weeks later they jump to 15.5 or 16.0 and they stay there...tested out to a couple years...still at about 16.

I have cast many bullets with that alloy over many sessions, always the same.

 

[Rick]

Antimony not only determines final hardness but the percentage of antimony will also determine how fast the alloy gets to final hardness. Something like a 1% Sb alloy will slowly and gradually harden over several weeks. A 3% or more Sb alloy will gain most of it's final hardness in a few days and then slowly age harden just a bit more over a few weeks. Antimony is also the key to brittleness meaning too much of a good thing ain't necessarily a good thing. All depends on what your shooting.

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[JWFilips]

When I ran that above mix ( to my best estimates) the calculator said:
1.34% tin
3.26% antimony
0.01% arsenic
95.4% lead

That is why I was a bit shocked because there should be ample Antimony ( Unless I was way wrong with the guess of that layered block actually being partly Isotope containers)
Maybe it was a cooler then normal mould ? I did only cast 12 (starting with a cold Alum Mould)

 

[Ian]

Maybe it was a cooler then normal mould ? I did only cast 12 (starting with a cold Alum Mould)

That explains the results you got. Bake them at 450F for 30 minutes and dump them in a pan of cool water, you'll see very different results. It would be very revealing to hardness test every day for a month.

 

[Brad]

Run a hundred or so. Water drop the last few from a hot mould. They should have a light frost to them. That will give a more realistic picture.
I heat treat my range scrap to 18 BHn with little trouble and it has less than 2% Sb. Great thing is that the bullets hold together really well.

 

[JWFilips]

Antimony not only determines final hardness but the percentage of antimony will also determine how fast the alloy gets to final hardness.

Sorry Guys,
I was unaware of the fact that lower Antimony content would cause the water dropped alloy to take "longer" to harden after a quench. I'm used to seeing a change pretty quickly with my other COWW based alloys.

Since I'm actually "busy" this week at work I'm going to have to postpone an oven hardening test for now but maybe I will see a change in what I have by the weekend to get an idea on how it is proceeding.
I always am learning things from you folks...sure glad we can discuss stuff like this and make it a learning experience. I really appreciate that.
Thanks
Jim

 

[Ian]

I doubt you'll see much further change if your bullets were cooled past the hardening stage by the time they hit the water. 2% antimony or less takes weeks to months show full hardness. 4% or higher generally is a week or less, depending on tin content. Also, the hotter they are just before the quench, the harder they get.

 

[fiver]

that consistency thing again..

 

[JWFilips]

Reporting back on this:
I did a casting session with this alloy ( water dropped) on June 5th and have been checking on the hardness once or twice a week.
Today is 3 weeks since they were cast and I'm getting a pretty connistant 15 bhn on the bullets but it sure was slow in coming ( not like my usual 50% pure / 50% COWW which is usually BHN 18 in one week from water dropping) So I guess that the Antimony was less then I calculated originally. However I'm very close to my target hardness & it isn't that big of a deal to have to wait 3 weeks since when I cast air cooled I wait this long. So all & all considering the alloy was totally free ( except for my labour) I can't complain
I'm thinking I may gain a bit more BHN if I were to heat treat in an oven instead of water dropping

 

[fiver]

yes the higher the quench temp the more bhn you can gain.
you want to be just under the slump point of the alloy and soak them for an hour then immediately dump them into cold water.
the speed of the quench and the alloy temp change from hot to cold is the key.

 

[Rick]

yes the higher the quench temp the more bhn you can gain.
you want to be just under the slump point of the alloy and soak them for an hour then immediately dump them into cold water. the speed of the quench and the alloy temp change from hot to cold is the key.

You only want to heat to just under the slump temp if your looking for the max BHN possible. You can regulate the amount of final BHN by using reduced heat, starting at about 425 and increasing in increments of 10 degrees you can choose your final BHN. This is very repeatable assuming the use of the same alloy each time.
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[popper]

I use isocore - about what you have- and add a tad (0.3-0.5%) of copper. 2700 from a 165 GC 308W & 2100 from a AC PB 145gr in BO. Go for it. Also works great in 9mm & 40SW stiff loads. As will harden real fast when H.T.ing and gets a little harder. It doesn't add malleability like Cu.

 

[Chris]

So here's a question about reversing the hardening process: Paco kelley and others have described casting a high antimony alloy (I think magnum shot) with 5% tin). Waterdrop bullets. Then standing the bullets in water and de-tempering the noses with a torch which softens them to an unknown degree for better expansion on game.

Presumably there is some softening or they wouldn't publish it. My primary question is whether the softened noses remain soft or do they age harden back up to at least the BHN of aircooled alloy? If they age harden, presumably the percent Sb has much to do with how fast the hardening and how hard the final nose BHN? So if a fellow wanted soft noses made this way, for how long does he have utility? The whole deer season or just a few weeks?

My questions regard the science of metallurgy, I'm not necessarily wanting soft noses right now. Bullet performance on game is a whole different discussion.

 

[JWFilips]

I have read those articles also and never could figure out how you don't get inconsistency from bullet to bullet by just using one torch flame

 

[Brad]

They will, over time, harden just the same as air cooled bullets of the same alloy. That is what that portion of the bullet has become.

Magnum shot is what, maybe 3% Sb? Add 1% Sn and you have an alloy similar to what many use except it contains far more As and will heat treat harden pretty fast.