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modifying alloy calculation (Read 1897 times)

Joe_S Oldtimer Offline Posts: 996 Joined: Jun 29^th, 2004	modifying alloy calculation Apr 1^st, 2020 at 9:17pm	Print Post
	I am a history major, not a math major as the following will demonstrate. I want to convert some 30/1 alloy to 25/1. Here is my calculation, can someone who knows more about this than I do ( which is everyone), please check my math to confirm? 30/1 alloy has one unit of tin for 30 units of lead. So 31 lbs of alloy contains one pound of tin. one pound out of 31 = .3223806% tin(one divided by 31) Using the same formula, 26 lbs of 25/1 has .38461538% tin. If I want to convert 20 lbs of 30/1 to 25/1 I need to add 1.6 oz of tin to 20 lbs of 30/1 calculated as follows: 20lbs of 25/1 has .745/lbs of tin(20 X .38461538%) 20 lbs of 30/1 has .645 lbs of tin (20X.3225806%) therefore, I need to add .1 lbs of tin to the 30/1 (.745-.645=.1) 1 oz of tin = .0625 lbs(1 lb divided by 16 oz=.0625) .1 lbs divided by .0625=1.6 oz If the match is correct, I need to add 1.6 oz of tin to the 20lbs of 30/1 to turn it into 25/1, the only problem being it will then be 1.6 oz over 20 lbs, thereby throwing the ratio off by a little bit. Agree? Thanks! Joe


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SSShooter Frequent Elocutionist Offline Posts: 2917 Location: Southern NJ Joined: Aug 1^st, 2010	Re: modifying alloy calculation Reply #1 - Apr 2^nd, 2020 at 8:07am	Print Post
	As they say........... close enough for gov't work. There is no magic in 25/1 or 30/1 or 20/1. The magic is whatever works in your rifle. What works as a load in one rifle is only a guideline for what may work in your rifle.

	Glenn - 2x CPA 44 1/2 w/22LR (Shilen ratchet-rifled & Bartlein 5R rifled), 38-40RH & 38-55WCF (Bartlein 5R rifled) & 40-65WCF (GrnMtn 'X') barrels
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GWarden Senior Forum Member Offline Posts: 317 Location: Marshalltown Iowa Joined: Apr 18^th, 2004	Re: modifying alloy calculation Reply #2 - Apr 2^nd, 2020 at 9:13am	Print Post
	Joe PM sent. bob

	Game Warden: what boys dream of being and old men wish they could have been
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texasmac Frequent Elocutionist Offline Posts: 1893 Location: Central Texas Joined: Aug 16^th, 2004	Re: modifying alloy calculation Reply #3 - Apr 2^nd, 2020 at 7:47pm	Print Post
	Joe_S wrote on Apr 1^st, 2020 at 9:17pm: I am a history major, not a math major as the following will demonstrate. I want to convert some 30/1 alloy to 25/1. Here is my calculation, can someone who knows more about this than I do ( which is everyone), please check my math to confirm? 30/1 alloy has one unit of tin for 30 units of lead. So 31 lbs of alloy contains one pound of tin. one pound out of 31 = .3223806% tin(one divided by 31) Using the same formula, 26 lbs of 25/1 has .38461538% tin. If I want to convert 20 lbs of 30/1 to 25/1 I need to add 1.6 oz of tin to 20 lbs of 30/1 calculated as follows: 20lbs of 25/1 has .745/lbs of tin(20 X .38461538%) 20 lbs of 30/1 has .645 lbs of tin (20X.3225806%) therefore, I need to add .1 lbs of tin to the 30/1 (.745-.645=.1) 1 oz of tin = .0625 lbs(1 lb divided by 16 oz=.0625) .1 lbs divided by .0625=1.6 oz If the match is correct, I need to add 1.6 oz of tin to the 20lbs of 30/1 to turn it into 25/1, the only problem being it will then be 1.6 oz over 20 lbs, thereby throwing the ratio off by a little bit. Agree? Thanks! Joe Joe, Your logic is correct but your math is a little off. Let’s go over your math. For starts, ignoring your initial typo and to confirm: 1/31=3.2258% and 1/26=3.846% So 20lbs of 25/1 has 0.769lbs of tin (not .745lbs), and 20lbs of 30/1 has 0.645lbs of tin as you noted. Therefore you need to add 1.984oz of tin to 30/1 (0.769-0.645=.124lbs of tin). So add 2oz of tin to the 30/1. Wayne
	« Last Edit: Apr 4^th, 2020 at 7:23pm by texasmac »
	NRA Life (Benefactor & President's Council) Member, TSRA Life Member, NSSF Member, Author & Publisher of the Browning BPCR book
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Joe_S Oldtimer Offline Posts: 996 Joined: Jun 29^th, 2004	Re: modifying alloy calculation Reply #4 - Apr 2^nd, 2020 at 8:13pm	Print Post
	Thanks Wayne! Joe


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JS47 Frequent Elocutionist Offline Posts: 1265 Location: Arizona Joined: Oct 12^th, 2012	Re: modifying alloy calculation Reply #5 - Apr 4^th, 2020 at 7:07pm	Print Post
	I don't remember if this was posted here or on another forum.

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