Adding lead to 30:1.

[Martini Sportco]

Hi all,
I can't seem to work this out.
I want to soften my lead / tin alloy from 30:1 to 40:1 by adding more lead.
What would the formula be ??
Thanks in advance. 👍🇦🇺

[megasupermagnum]

Well if you want to make 40 pounds of alloy, take 30 pounds of your 30:1 and add 10 pounds of pure lead. For 20 pounds, obviously half it. For 10 pounds, half that.

[Land Owner]

You are correct in adding 10 pounds of lead to a 30-pound (30 to 1) alloy to make a 40 to 1 alloy, but only for that one weight. You are incorrect for 20#'s & 10#'s of 30 to 1 alloy.

A 30 to 1 ratio is 3.3333% Tin.
A 40 to 1 ratio is 2.5000% Tin.

The change is 3.33333% divided by 2.5000%, which equals a multiplication factor (for lead) of 1.33333. Multiply the weight of 30 to 1 alloy by 1.3333.

To change 30 to 1 Pb/Sn alloy into 40 to 1 alloy increase lead content by 1.3333.

30 to 1.................Add Lead..................40 to 1
Weight.................Weight..................... Weight
Pounds.................Pounds..................... Pounds
10........................3.33.................... ....13.33
20........................6.67.................... ....26.67
30.......................10.00.................... ...40.00
40.......................13.33.................... ...53.33
50.......................16.67.................... ...66.67
etc.

TEST multiplication factor:

30 to 1...............30 to 1..........Ratio.................40 to 1.................40 to 1...........Ratio
Tot. Wt...............#'s of............Tin...................Tot. Wt.................#'s of..............Tin
Pounds...............Tin................to Lead..............Pounds.................Tin...... ..........to Lead
10.....................0.33..............3.33%...............13.33........... ......0.33..............2.50%
20.....................0.67..............3.33%...............26.67........... ......0.67..............2.50%
30.....................1.00..............3.33%...............40.............. .......1.00...............2.50%
40.....................1.33..............3.33%...............53.33........... ......1.33..............2.50%
50.....................1.67..............3.33%...............66.67........... ......1.67..............2.50%
etc.

The weight of Tin stays the same. The total weight of the alloy increases. The ratio of Tin to Lead decreases

[Martini Sportco]

Thanks Guys.
So 10 kilograms (I'm in Oz) x 1.333 = 13.33 kilograms.
So I add 3.33 kg of lead ?

[kevin c]

There’s argument whether the bullet alloy called “30 to 1” is actually 1# tin IN a total weight of 30# of metal, which is 3.333% tin, or 1# TO 30# of lead for a total weight of 31#, which is 3.226% tin. That changes how to mix into “40 to 1”.

In the case of 1 part tin IN a total of 30 parts alloy, you might start with 30# made up of 1# tin and 29# lead, and want to end up with 1 part tin IN a total of 40 parts alloy, made up of 1# tin and 39# lead. Here you’d add 10# of pure to the 29# of lead and 1# of tin in the first alloy to end up with 39# lead and 1# tin. Generalizing, you’d add 1# pure to every 3# of the original alloy, a 1 to 3 ratio, or 33.33% more pure added to the original alloy weight.

If you have thirty parts lead TO one part tin (31# total) and you want forty parts lead TO one part tin (41# total), you add another ten parts lead to the thirty of lead you already have to get forty parts lead along with the one of tin you already have. The ratio of pure added to original alloy is 10 to 31; generalized, add 32.26% more pure to the weight of the original alloy to get 40 parts lead TO 1 part tin.

ETA: kilos or pounds, it’s the same confusion…

[Martini Sportco]

I believe 30 : 1 becomes 31. ��������
Thanks.

[Land Owner]

For what it is worth, and it is not worth arguing about, these ratios of lead and tin are not Rocket Science, and before I retired, I was a Rocket Scientist.


EXAMPLE
You want 25 pounds (kilos/stones/smoots) of 30 to 1 (lead to tin) alloy.
The amount of tin desired is 1 divided by 30, which equals 3.3333 percent TIN.
The amount of lead is 100 percent minus the 3.3333 percent of tin, which equals 96.6667 percent LEAD.

MULTIPLY 25 pounds of total alloy desired by 0.966667 to determine the WEIGHT of LEAD
MULTIPLY 25 pounds of total alloy desired by 0.033333 to determine the WEIGHT of TIN

This works for ANY RATIO and ANY total alloy weight.

Here are a few examples at 25 pounds of alloy:

EXAMPLE
ALLOY
POUNDS....RATIO................................... .........POUNDS....POUNDS
TOT. WT.....LEAD...............% TIN.......% LEAD....TIN...........LEAD
25............50 to 1.............2.00%.......98.00%....0.5........... 24.5
25............40 to 1.............2.50%.......97.50%....0.625.......24 .375
25............30 to 1.............3.33%.......96.67%....0.833.......24 .167
25............20 to 1.............5.00%.......95.00%....1.25.........2 3.75
25............10 to 1...........10.00%.......90.00%....2.5...........2 2.5