Bullet hardness over time?

[CaptnJack]

The other day I was making some 16-1 led ingots just using led and tin. I did a hardness test with the Lee hardness tester and they came out to 12-1 BHN. I ran out of the tin to add to get it to a 16-1. Anyway, I have some 20-1 alloy I bought from BA a few years ago and melted it down into 1lb ingots. I also did a hardness test on it and it came out to be 12-1 BHN which is supposed to be 20-1 which was stamped right on the ingots. I was reading some on this subject and since I am new to casting my own bullets and I have no idea on this. Is it true cast alloy will lose it's hardness after it sits a long time in my case for over two years? Suggestions? or ideas on this?
Thanks.

[rgchristensen]

JACK;
"16-1, 20-1", etc are not hardness specifications, but are recipes. E.g., "16 to 1" implies a mixture of 16 parts lead and one part of tin. Brinnell hardness is measured with an indenting instrument. Alloys of lead and tin don't change hardness much with time, but other mixtures can, especially those containing antimony and a trace of arsenic.
CHRIS
RGChristensen

[beltfed]

Perhaps a better way to designate these lead alloys is, for example:

16+1 lead/tin
or
20+1 lead/tin

or
my
9+1 WW/Lino

beltfed/arnie

[CaptnJack]

Using the Lee hardness test kit it came out to.065 and then you look at the conversion chart the comes with the tester, for the .065 indent you just measured with there scope you read the metered lines you compare that reading to the chart and you get 12-1 ratio. Not sure why I got that reading with BA 20-1 alloy?

[rgchristensen]

Charlie Dell gives these BHN hardness numbers for these lead-tin proportions :
very pure lead, BHN = 4.2
common lead, BHN = 5.0
30 - 1 6.7
25 - 1 7.1
20 - 1 7.9
15 - 1 9.3
10 - 1 12.4

Bear in mind that you can't go "backwards", and find the lead-tin proportion by just measuring the BHN hardness, as you can't be sure that the alloy is free of copper, silver, antimony, or other components. Also be aware that the more "hardening agents" you add to your lead, the more the melting point is lowered.
CHRIS
RGChristensen

[Kurt]

Don't put to much faith in that Lee microscope for BHN. My 1/16 using 99% + tin and lead I get a reading of .080. The only thing I use it for is a reference between known and unknown by looking at the dimple diameters compared to a diameter of a known mix. Forget the BHN.

[mdeland]

I can't get the microscope deal to be reliable for me either. I use a caliper to measure the dimple instead and it matches my LBT scale quite nicely for checking hardness. The trouble with lead tin mixes is that they soften over time unless kept in a deep freeze where as antimony allows retain there hardness for many years. The late Dan Theodore, who was a great friend and experimentor to many on here, found that lead tin alloys will soften in one years time, a couple of points, unless kept in a freezer.
I miss Dan!

[CaptnJack]

Thanks for the info will do some checking with my calibers also.

[CaptnJack]

I have been stewing over the bullet hardness for the 16-1 alloy bullets I been making. I remember reading about a way to check it without any special equipment, in fact, I got it from TexasMac's Web Site. I did it the easy way it showed and I got an alloy of 16.1 in the bullets I have just been casting over the past few days. I actually measure the weights of lead/tin before I mix it together but I had no way of really telling( I had some iffy lead just was not real sure) and since the Lee hardness tester was off. I am almost right on with the 16.1 ally bullets. rounded of it came out to a 10.93. So here is what I did.

Here is the short of it.
listed below are the specific
gravities (SG) values of several well-known bullet casting alloys. If you don’t
have access to an alloy calculator such as the one referenced in the article, once
the SG is measured you should be able to make a rough estimate of the lead/tin
percentage from the following values.

SG of pure lead is 11.3450
SG of 30:1 (lead/tin) is 11.1485
SG of 25:1 (lead/tin) is 11.1115
SG of 20:1 (lead/tin) is 11.0574
SG of 16:1 (lead/tin) is 10.9918
SG of pure tin is 7.337

Very Simple SG Measurement Technique
The simplest procedure uses a small container of water placed directly on the
scale platen. The container should be as lightweight as possible but large enough
to hold a submerged bullet without the bullet coming in contact with the
container. I used a prescription pill container. Figure 2 illustrates the 3-step
measurement procedure.

1. Assuming the scale is warmed up and calibrated, place the bullet on the
platen. Measure and record the dry weight.
2. Place the container of water on the platen and zero out the tare weight.
Note - If the scale does not have a zeroing or tare weight feature, the
measurements can still be made but the scale must be capable of accurately
measuring the total weight of the container of water and bullet to an accuracy of
0.1 grains minimum. In this case, the weight of the container of water must be
measured and subtracted from the wet measurements.
3. Using sewing thread or thin monofilament line, suspend the bullet fully
submerged. Note the “wet weight” reading while ensuring the bullet does not
contact the inside of the container.
4. Using the dry and wet weights, determine the SG of the bullet alloy.
Formula A applies in this case. Using a dry weight of 427 grains and a wet
weight of 37.8 grains, SG = 427 ÷ 37.8 = 11.2963; rounded to 11.30.
Note - Although the test sample and faucet water will be at room temperature,
the resulting accuracy of the procedure will be sufficient for our needs assuming
the scale has a resolution of at least 0.1 grains, several careful measurements are
made and the results averaged,. Out of curiosity, I did try very cold distilled
water and there was no measurable difference in the resolution of the RCBS
scale.

[bruce m]

mike,
this is nothing personal, but i remember differently what dan said about alloys.
i could be wrong, but i thought he said after initial adjustment of hardness, lead and tin stayed relatively the same for a fair while
the problem is with lead/tin/antimony alloys that they get harder and softer and harder again etc., as well as taking a long time to become stable if they ever do.
best stability apparrently came from less tin than antimony in the mix.
keep safe,
bruce.

[mdeland]

All I use is antimony alloys and have some I cast of wheel weights over twenty years ago that are with in 2 Bhn of when they were cast which is a BHN 12-14. they are still 12-13 . No, it's the lead tin mixes that change quickly unless kept in a freezer but can be re-heat treated to bring them back.
I have read that If you heat treat and cold quench WW's you can get them into the 20's BHN.

[beltfed]

Mike,
Indeed , one can heat treat WW based alloys and get higher hardness than Lino.
Dennis Marshall's articles in TAR, and subsequently published in the old NRA CBH
details this:
Typically: an alloy of 4.4% Antimony/trace of arsenic heat treated at 482 F for 2hrs/then quenched will
hit a BHN of 24. at 3 days.
My 9+1 ww/lino alloy when I was heat treating the bullets for Silhouette will be close to Marshall's alloy of 5% antimony/0.5% tin where he recorded hardness of 36 BHN after the 482 Heat treat.
beltfed/arnie

[Kurt]

Here is another way to test hardness. http://www.corbins.com/lead.htm#hard

I don't really concern my self with the alloy. The lead you get now days I think is recycled scrap lead mostly. Very few lead mines are running anymore in this country and most of the scrap yard lead goes to China. Not many scrapyards sell lead to the walk in anymore.
If I want my mix I take 18 lbs of supposedly 99.9% pure as advertised and add one roll of 95/5 no lead solder that is 95% tin 5% antimony. The solder is about as close to the specs as you can get. The batch I mix weighs around 70 lbs and that alloy is marked and used for a the bullets I need and marked so I use the same mixed alloy. If the BHN is 14 or 16 it makes no difference as long I use it for the same load. I know that the 18 lbs of lead and that roll of solder holds the setback almost perfect except for the expansion of the PP bullet to fill the grooves but the ogive holds it's shape.

[MSalyards]

? 52lbs of 95/5 tin and ant ,and only 18 lbs lead? That's 70 lb alright , but 95% tin and 5% ant . Did I miss something?

[Kurt]

Ya maybe you misplaced your glasses I said I mix a batch AROUND 70 lbs.
If your wanting to know what my mix is, It's 72 lbs lead 4 one pound rolls of 95/5 no lead solder. So that would make a total of 76 lbs if I don't skim off to much dross fluxing it. Now this is for the .45 caliber.
For the .40 which needs a harder mix for the same results the total weight will be 72 lbs.
So I guess I can say that when I mix a batch that it's around 70 lbs.