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Old April 1, 2013, 07:27 PM   #1
rambler68
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1:10 alloy question

As I understand a 1:10 alloy of lead and tin has a hardness of 11-12, I have read that after 20 days it will loss about 4 bhn for a hardness of 7-8 is this correct or is it harder when just cast?
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Old April 1, 2013, 07:57 PM   #2
CS86
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I think you have part of that backwards.

Quote:
I have read that after 20 days it will loss about 4 bhn for a hardness of 7-8 is this correct or is it harder when just cast?
Usually the longer it sets the harder it gets. I've read water quenched takes a longer time to harden, but hardens more so then air cooled.

Not sure on the BHN. Tin is expensive and I'd almost start with a 1:20 mix or more.

You never mentioned what you are casting for. It can make a difference.
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Old April 1, 2013, 08:47 PM   #3
243winxb
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A lead tin alloy will get softer over time. How long i dont know. Alloys with antimony dont do this. Antimony, if water dropped, full hardness is reached later depending on the % of antimony. 2% about 2 weeks. 6% full hardness in 1 hour. http://www.keytometals.com/page.aspx...site=ktn&NM=88 Correction- Lead tin alloys-
Quote:
. Lead-tin alloys, for example, may recrystailize immediately and completely at room temperature
I guess this means the alloy retains the same BHN ? But i seem to remember reading it gets softer with time, some where??

Last edited by 243winxb; April 3, 2013 at 11:08 AM. Reason: . Lead-tin alloys, for example, may recrystailize immediately and completely at room temperature
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Old April 1, 2013, 10:59 PM   #4
mehavey
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See below for actual BHN measurements:



Note that 1:10 will fall in the mid 8's.

Note also that pure lead-tin alloys will neither harden nor soften with age. Nor will they respond to quenching. They are what they are. Add antimony, however, and you have a whole different ball game.

Special note: Lyman#2 (5/5/90) is peculiar in that it also hits its BHN(~15) right away and stays there (mostly) irrespective of aging

Last edited by mehavey; April 2, 2013 at 05:57 AM.
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Old April 3, 2013, 02:32 AM   #5
rambler68
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I am loading a Uberti 1858 Remington revolver and am using a .45 conversion cylinder and am using a Lee 255 gr mold, when I cast using 1:20 or even 1:16 my bullets are in the 269 gr range using the 1:20 and 263 gr range using 1:16, I want softer bullets that weigh in around 255 gr and pure lead is to heavy for the molds I am using but if I can cast bullets using the 1:10 for a hardness of 11-12
and they will soften up to about a 8 bhn in a month it should work out great at my 750 fps velocity using 30 gr of KIK black powder.
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Old April 3, 2013, 06:56 AM   #6
reloader28
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Hmmmm, my WW always end up around 12 or so.
I dont think I've even heard of 9 BHN clip on WW.
Unless thats what the 50/50 bar means. My 50/50 clip on/pure lead bullets run about 9.

I call it pure lead. Its stick on and lead pipe.
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Old April 3, 2013, 05:30 PM   #7
rambler68
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Clip on wheel weights composition have varied over the years most likely based on alloy prices.
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Old April 3, 2013, 06:26 PM   #8
mehavey
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Quote:
I dont think I've even heard of 9 BHN clip on WW.
That was a left-over ingot of WW cast about 10 years ago -- i.e., "aged" -- as was noted. Aging does soften antimony-lead alloys considerably over extended time, so that 8.9 was real.

Believe me when I observe that with rare exception, alloys whose BHN numbers make-the-rounds on the internet are generally far softer than the "accepted" internet sources say they are. Numbers get repeated without actual test. If you want truth and no-kidding experience, swing over to castboolits.gunloads.com and open up the "Alloys" section.

I will offer in closing that the truly "Hard-Cast" bullets by the professional caster are hard -- witness the ~24BHN of Beartooth's 400gr LFNGC at the bottom of the chart above.

Last edited by mehavey; April 3, 2013 at 07:19 PM.
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Old April 4, 2013, 07:07 AM   #9
Mike / Tx
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Quote:
I am loading a Uberti 1858 Remington revolver and am using a .45 conversion cylinder and am using a Lee 255 gr mold, when I cast using 1:20 or even 1:16 my bullets are in the 269 gr range using the 1:20 and 263 gr range using 1:16, I want softer bullets that weigh in around 255 gr and pure lead is to heavy for the molds I am using but if I can cast bullets using the 1:10 for a hardness of 11-12
and they will soften up to about a 8 bhn in a month it should work out great at my 750 fps velocity using 30 gr of KIK black powder.
THe thing to remember when using almost any commercial made mold is that they are cut for a specific alloy,(ie. Lyman 2 or similar). When you pour using straight WW alloy or a variation of it, your bullets WILL drop heavier than what the mold usually say's they will. Most of my 255's from the Lee mold drop at 260 to 270 depending on the alloy. I simply drop the powder a touch to cover this and all is well.

You would have to add in some antimony to get your weights closer or you might look at a custom mold where you give them your preferred alloy and they will cut the mold to drop the proper weight bullet. Not the cheapest answer to your question, but if you want a 255gr bullet using your alloy about the only way to get there without adding in more antimony for a harder bullet. The closer to pure you go the heavier it is going to drop.
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