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Mick B
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changing alloy mix
May 20th, 2022 at 4:08am
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I made up a batch of 25-1 alloy  to try in my 40-65 to compare with the 20-1 I had been using, as there was nod difference in  accuracy I  have decided to return the mix back to 20-1.
My question is, how much tin must I add to get back from 25-1 to 20-1. I have about 15kg of the 25-1 alloy on hand.
Cheers
Mike
  
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Schuetzendave
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Re: changing alloy mix
Reply #1 - May 20th, 2022 at 9:16am
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Mike:

25:1 = 1/26 or 3.85% tin
20:1 = 1/21 or 4.76% tin

So 4.76%-3.85% = need to add 0.91% tin

Weigh how much 25:1 alloy you have and multiply it by 0.91% to determine how much tin you need to add.

15 kg. (33 lb.) x .0091 = need to add 0.1365 kg. or 136.5 gm. (0.30 lb.) of tin

Does not matter if you use Imperial or Metric units of measure.

Dave
« Last Edit: May 20th, 2022 at 9:38am by Schuetzendave »  
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Mick B
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Re: changing alloy mix
Reply #2 - May 24th, 2022 at 8:34pm
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I recently asked for a way to change the 25-1 alloy mix I have from 25-1 to 20-1, I received a vary nice reply which unfortunately is a bit beyond my maths ability to try.
I am now re posting with more info as to the amount of alloy I have in my melting pot and asking how much tin I need to add to the pot to get the existing mixture down from 25-1 to 20-1. 
Currently there is approximately 20 lb of lead in the pot so how much tin do I need to add either in grams or ounces.
Sorry for being so dumb, old age is my excuse.
Mike.
PS  As I'm shooting fixed BP loads we don't have to be exact, just approximate will do fine.
  
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MikeT
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Re: changing alloy mix
Reply #3 - May 24th, 2022 at 10:25pm
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Add 3.2 oz of tin.

Keep on hav'n fun!
MikeT
  
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Schuetzendave
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Re: changing alloy mix
Reply #4 - May 24th, 2022 at 11:52pm
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20 lb. x .0091 = .182 lb. tin x 16 oz./lb. = 2.9 oz. tin
  
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Mick B
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Re: changing alloy mix
Reply #5 - May 25th, 2022 at 7:33pm
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Thanks all
Mike
  
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