Question for all Y'all Lead Metallurgist

[Southron Sr.]

About a week before the last Spring Nationals I fired up the old casting machine to cast some Minie Balls for the Nationals. I was using batch of lead that was supposed to be "Pure" lead.

What I quickly found out was that even though my melt was at the proper temperature, the mould heated up properly, I was running something like 40% rejects. Not a good thing at all.

In desperation I jumped into the old horseless carriage and made a bee line to the local hardware store where I picked up a 1 pound roll of 50/50 solder that was composed only of lead and tin.

I refilled my pot which has a 40 pound capacity. Then I threw in HALF the roll of solder-which I figure contained 4 ounces of Tin.

I mixed the solder into my melt (but did not flux again) and started casting bullets again.

"PRESTO" My bullets started coming almost out "Perfect" with maybe a 2% reject rate. Of course because of the Tin, they were also brighter.

Here is my math: 40 pounds of lead equal 640 ounces of Lead. So divide 4 ounces of Tin into 640 ounces of Lead = a 1 in 160 Tin/Lead ratio.

QUESTION: If Pure Lead has a Brinell hardness of 5.0 then what is the Brinell hardness of my 1 in 160 alloy mixture???

Inquiring Minds Want to Know!

THANKS for your answers in advance!

P.S. I am assured that my Minie Balls, even with a 1 in 160 alloy is "Soft" enough for Minie Balls.

[Lou Lou Lou]

Try the CastBOOLits.com website. They love figuring out this stuff.
Yes the spelling is correct

[R. McAuley 3014V]

About a week before the last Spring Nationals I fired up the old casting machine to cast some Minie Balls for the Nationals. I was using batch of lead that was supposed to be "Pure" lead.

What I quickly found out was that even though my melt was at the proper temperature, the mould heated up properly, I was running something like 40% rejects. Not a good thing at all.

In desperation I jumped into the old horseless carriage and made a bee line to the local hardware store where I picked up a 1 pound roll of 50/50 solder that was composed only of lead and tin.

I refilled my pot which has a 40 pound capacity. Then I threw in HALF the roll of solder-which I figure contained 4 ounces of Tin.

I mixed the solder into my melt (but did not flux again) and started casting bullets again.

"PRESTO" My bullets started coming almost out "Perfect" with maybe a 2% reject rate. Of course because of the Tin, they were also brighter.

Here is my math: 40 pounds of lead equal 640 ounces of Lead. So divide 4 ounces of Tin into 640 ounces of Lead = a 1 in 160 Tin/Lead ratio.

QUESTION: If Pure Lead has a Brinell hardness of 5.0 then what is the Brinell hardness of my 1 in 160 alloy mixture???

Inquiring Minds Want to Know!

THANKS for your answers in advance!

P.S. I am assured that my Minie Balls, even with a 1 in 160 alloy is "Soft" enough for Minie Balls.

At a ratio of 1 part Sn (Tin) to 160 parts Pb (Lead), the Brinell hardness of the tin-lead composition won't make much of any change from BHN 5. According to the web site link below

http://www.lasc.us/brennan_saeco_table.htm

This is a representation of the chart that Saeco ships with their Bullet Hardness Tester.
The chart demonstrates the relative hardness that may be expected when alloying various ratios of Tin/Lead by using the following formula.
BH = ( 222.5 x R - 7.82 x R x R ) / ( 1 + 23.12 x R ) + 5
Let "R" equal a Ratio which is the weight of the Tin in the alloy divided by the total weight of the alloy.-
Then:
1 part tin plus 19 parts lead (by weight) equals a 1 in 20 alloy.
Then 1/20 = 0.05 ... So then R = 0.05..... Therefore:
BHN = ( 222.5 x 0.05 - 7.82 x 0.05 x 0.05 ) / ( 1 + 23.12 x 0.05 ) + 5
The Brinell Hardness Number of a 1 in 20 Tin-Lead alloy = 10.15

An alloy made of half a pound bar of 50/50 Sn-Pb solder plus 40 lbs of lead equates to 40.25 lbs of lead plus a quarter pound of tin or approximately equal to 1 part tin to 160 parts of lead (or 1750 gns/281750 gns)

1/160 = 0.00625
Therefore,
BHN 1/160 Alloy= [(222.5 x 0.00625 – 7.82 x 0.00625 x 0.00625) / (1+23.12x0.00625)]+5

= [(1.3906 - 0.0003) / (1+0.1445)] + 5
= [(1.3903/1.1445)] + 5
= [1.2148] + 5
= 6.2148

[DAVE FRANCE]

When we buy soft lead it is always harder than 5 and has some impurtities. Adding a small amount of tin should make it cast a little better. I am surprised at the improvement you described. You probably did something wrong the first time you cast bullets with the new lead.

The addition of tin should also have made it sligthtly harder.

If you drop 1 pound ingots or bullets on concrete, and it makes a ding sound instead of a thump, it is too hard for Minies. If you want to know how hard your lead is and you don't have a lead hardness tester, send it to someone to test for you. I've had people send me bullets a couple times in the last couple years. Two Minies would be enough to test.

Send me a PM if you want me to check the hardness for you.

David

[DaveCVG]

You have run an interesting experiment ... thank you for sharing the data and results with fellow skirmishers. My calculations show a hardness of 5.6 BHN for your mix, essentially agreeing with Mr. McAuley's value of 6.1. However, I also have the same question as Mr. France ... this amount of tin seems too small to have nearly perfected your casting with this lot of lead. Please allow me to ask one question ... historically, with this 40# setup and your standard mold, did you get the near-100% molding acceptance rate with other lots of pure lead? I'm thinking ... could the solder have scavenged some impurity from this latest lot of lead? Also ... thanks for the information that this amount of tin does not affect bullet performance. Best, Dave Mertz