Alloying Math Question

[broken-mold]

I'm new to casting and reloading for BPCR although I've cast bullets and balls for my muzzleloaders for years. I've owned and shot a .45/70 H&R topper (factory smokeless loads) for along time and always wanted to reload for it so I could shoot it more but just couldn't get in the mood since it was just "a cheap little carbine". Recentl I swapped for a new 1871 H&R "Buffalo Rifle" also chambered for .45/70 so now I guess it's time to start reloading. I pulled my press out of 25+ years of storage and have been ordering odds and ends to get started in earnest. My question, though, relates to bullet alloys. I plan to begin shooting a 1:30 mix. I have several rolls of solder from a business buy-out and so am planning to use some of it for the tin. While smelting some pure lead recently I also smelted 3- 1 lb. rolls of 40% Sn / 60% Pb and cast it into 1/2 and 1 lb. bars. I fully understand what 1:30 means but my question is about the math. If someone would be so kind please check my elementary school math and correct me if I ere.

For instance, if I start with 12 oz. of 40/60, according to my math, it contains 4.8 oz. of tin and 7.2 oz. of lead. If that 4.8 oz. is my "1" I would need 29 more parts of lead which is 139.2 oz. If I subtract the 7.2 oz. of lead I already have in the mix from the solder from the 139.2 that leaves 132 oz. of additional lead to add to the 12 oz. of 40/60 solder. If my calculations are correct this should yield 144 oz., or 9 lbs., of 1:30 tin/lead for my 10 lb. Lee pot. Is my math even close?

[lwknight]

You are spot on 03.33% tin is what I figured.
Which is 29:1 or aka the generally misnomered 30:1

30:1 means 30 parts to 1 part which totals 31 parts

[303Guy]

So that should read "30 to 1".

[broken-mold]

You are spot on 03.33% tin is what I figured.
Which is 29:1 or aka the generally misnomered 30:1

30:1 means 30 parts to 1 part which totals 31 parts

Hmm. That little detail escaped my notice. That being the case, using my original numbers, should I use the 4.8 oz. of tin and multiply it by 30 instead of 29? That would mean I should add 144 oz. of lead minus the 7.2 oz. in the 40/60 solder for a total of 136.8 oz additional lead.

12 oz. 40% Sn / 60% Pb solder (de-fluxed)
136.8 oz. Pb
148.8 oz. (9.3 lb.) 30:1?

[bumpo628]

Hmm. That little detail escaped my notice. That being the case, using my original numbers, should I use the 4.8 oz. of tin and multiply it by 30 instead of 29? That would mean I should add 144 oz. of lead minus the 7.2 oz. in the 40/60 solder for a total of 136.8 oz additional lead.

12 oz. 40% Sn / 60% Pb solder (de-fluxed)
136.8 oz. Pb
148.8 oz. (9.3 lb.) 30:1?

No, you had it right the first time.
30:1 is actually "1 in 30" or 1 part tin to 29 parts lead
Just take 1 divided by 30 = 3.33%

When people talk about mixing in a 2:1 ratio, they mean 2 parts to 1 part. I don't know where tin-lead alloys went astray, but that's the way it is.

Desc. , Tin %
40 to 1 = 2.50%
30 to 1 = 3.33%
25 to 1 = 4.00%
20 to 1 = 5.00%
16 to 1 = 6.25%
10 to 1 = 10.00%

[Sonnypie]

"I don't know where tin-lead alloys went astray, but that's the way it is."

Probably the same derailment that brought us "new math" years and years ago. :shock:

[lwknight]

No, you had it right the first time.
30:1 is actually "1 in 30" or 1 part tin to 29 parts lead
Just take 1 divided by 30 = 3.33%

OK , if that be the case , what is 2:1???
Does that mean 1 of 2 or does it mean 1 part to 2 parts??
If its 2:1 do you end up with 2 total units?? Why not just say 50/50?

I know that 30:1 is really 30 parts + 1 part because it would be otherwise 29:1.
However as I said before about the mass misnomer you can probably count the popular 30:1 as really being 29:1 but realistically no one could ever tell the difference.

[bumpo628]

OK , if that be the case , what is 2:1???
Does that mean 1 of 2 or does it mean 1 part to 2 parts??
If its 2:1 do you end up with 2 total units?? Why not just say 50/50?

I know that 30:1 is really 30 parts + 1 part because it would be otherwise 29:1.
However as I said before about the mass misnomer you can probably count the popular 30:1 as really being 29:1 but realistically no one could ever tell the difference.

You described the problem perfectly right at the start. I was just trying to restate your post to help get the OP back on track.

It is really weird that people use ratios like this two different ways. The 2:1 example I used was to illustrate that when people use ratios for anything besides black powder tin-lead alloys, they actually mean two parts of this for every one part of that. So it would be a total of three parts. Somehow 10:1 for BP is actually 9:1 for everyone else. :veryconfu

[felix]

Actually, the gun literature talks about an approximation to volumes and/or weights as measurements and not actuals. This is so because exactness makes it mandatory that we talk about the dimensions of molecules as moles. However, nobody in their right mind is going to play around with "moles" for our applications. In other words, close enough is close enough. ... felix

[Matt_G]

It seems to me that when we say "1 in 20", we are really stating a dilution, specifically a dilution factor.


Ratios are often used for simple dilutions applied in chemistry and biology. A simple dilution is one in which a unit volume of a liquid material of interest is combined with an appropriate volume of a solvent liquid to achieve the desired concentration. The dilution factor is the total number of unit volumes in which your material will be dissolved. The diluted material must then be thoroughly mixed to achieve the true dilution. For example, a 1:5 dilution (verbalize as "1 to 5" dilution) entails combining 1 unit volume of solute (the material to be diluted) + 4 unit volumes (approximately) of the solvent to give 5 units of the total volume. There is often confusion between dilution ratio (1:n meaning 1 part solute to n parts solvent) and dilution factor (1:n+1) where the second number (n+1) represents the total volume of solute + solvent. In scientific and serial dilutions, the given ratio (or factor) often means the ratio to the final volume, not to just the solvent.

[runfiverun]

dudes:
they just got 30 lbs of lead at the general store and a lb of tin and threw them together.
sometimes a bit more or a bit less got threw in and their guns shot better or worse they saw this and started mixing in more or less of the stuff.
when their buddies at the rondevous seen the way their rifles shot they asked about the other guy's alloy mix at some point and he said bout 30-1, 70 grs of the red colored can of powder, and those yellow boxed primers.
with the boolits seated till i couldn't push them no deeper.

the difference in bhn from 30-1 and 29-1 is gonna be about 1/2 a bhn.