How much

[Freedom]

My math is a little primitive...but just about 1oz. of tin is needed to change 5lbs 20:1 to 16:1. I know there is a perfect formula for this, but I don't know it.

My estimate is based on:.... 16-1 equals ...1lb lead /1oz. tin...so to make 5lbs of 16-1 you need 5oz. tin
20-1 equals 5% tin....so in your 5lbs of alloy, you already have 4oz tin (5lb=80oz.alloy x 5%tin =4oz.)
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