Water Quenched 20:1. I Expected A Larger BHN Increase?

[jonp]

Up until now I have been air cooling my boolits but with a new to me pistol I decided to vary the BHN upwards a little by water quenching instead of increasing the alloy as my pot was full of 20:1 just to see what it would do.

I started with 20:1 alloy which yielded 10-10.5 BHN with my other boolits. I heated the alloy to 675, cast and then dropped them into room temperature water. After letting them harden for 24hrs I tested them and came out with 14 BHN. From reading the threads on water quenching I was expecting more in the neighborhood of 18-20 BHN.

Does this sound right? An increase of only 4 BHN? This is fine with me as it approaches Lyman #2 and is a good place to start for me anyways but I find this curious

[texassako]

You need some arsenic to get a good increase in bhn from water quenching. COWW is my usual source for that.

[country gent]

20-1 has no antimony and little arsnec to promote hardening. A small amount of antimony added can make a big jump in hardness when water quenching. Tin helps fluidity and fillout adding a small increase in hardness, Pure lead isnt going to change alot. Antimony is what does actual hardening and can be heat treated. An addition of as little as 1/2% antimony and water quench will make a diffrence probably.

[Edward]

Let it sit 20-30 days and check ,bet it"s a lot harder then !

[jonp]

Dang it, I read that and should have remembered it. WW is about as hard as I have gotten so far and have not really had a need yet as I have not ventured into high velocity/rifle yet being kept busy with pistol as I seem to keep acquiring one here and there that needs testing.

Thanks for the quick answers.

[DougGuy]

Yep, check them in a couple of weeks or a month, likely will be harder, and don't be surprised if they have "grown" a few tenths of a thou bigger.

[MtGun44]

Yep, without antimony you will get little or no hardness increase. Arsenic helps
the antimony, but it is mostly the Sb. Tin-lead "is what it is" pretty much.

[runfiverun]

14 is all your gonna get, water dropped or air cooled. [you just got there faster]
you need antimony to water harden [speed cool] lead alloys.

[jonp]

I was looking to test various BHN in my pistol so this will work. I'll try out some COWW then some 50:50 water dropped.

[Pee Wee]

If you can get you hands on some lynotype it will increase your bhn. You can make it as hard as you want. I was fortunate to have access to a huge supply of it from one of my shooting club members.

[Naphtali]

Until this thread, I was unaware that lead:tin mixes were hardenable. I had been informed that arsenic and/or antimony necessary.

[Dusty Bannister]

Only an assay of the mix will tell you if it is "pure" or already recycled and just soft scrap. If it is lead scrap, it probably already has "some" antimony and that might be where the surprise came in. Kind of open to speculation since the original mix was only given as "20-1" and that would be pretty much normal and acceptable for many hobby casters.

[jonp]

I'm rolling through as many variables as I can find time to just to see what happens. WC Brass, Reg Brass, Soft Pb, 20:1, 10:1, COWW, 50:50, different powders and charges, different primers, etc.

I'm now at the water quench stage and rather than mix up a whole batch of a different alloy I thought quenching just a couple of them might harden the boolits up enough for my test.

[dubber123]

I'm headed the other direction, I quenched or oven hardened everything for a while, then only the faster/higher pressure stuff. Odd thing is, some of my best results lately have come from air cooled 50/50 + 2% tin. It has a Bhn of about 9. I've run it to close to 1,500 fps. from a revolver, and close to 2,200 fps from a rifle. I'm liking it a lot.

[jonp]

Cool beans. Ive had good results with 10-10.5 bhn. I have never tried heat treating them alrhough the wife is out of town this week so it might be a good time to try it

[grouch]

The best information I have is that you need more antimony than tin to quench from the mold or heat treat. Otherwise the alloy will soften given enough time. I haven't tried to harden 20:1, so can't speak to it first hand, but my experience parallels Dubber123 - I get close to 2000fps with my 20:1 from good smooth .30cal barrels, and often better accuracy than with the antimonial alloys.
Grouch

[drinks]

Jonp, do not even THINK about using your wife's oven. She WILL find out and you will be in deep do-do!

[HeavyMetal]

Just for grins what are you shooting these in?

For most pistol stuff your 14 BHN is about right, target loads for 38 Special do better at 7 or 8 BHN.

Hardness usually needs to be tempered with the pressure your planning to run your load at plus the correct fit!