Shiloh Rifle Forums

I just finished casting up about 175-200 bullets and checked the hardness at 6 bhn and am curious what they will be at day 3 and 7. Probably should check at day 14 as well. Any of you done this incremental hardness testing. I remember DT doing quite a bit of this kind of thing but have forgotten what his results were, course alloy content percentages would make all sorts of differing results but it would be interesting to revisit this me thinks.
I also seem to remember him saying that with lead tin alloy they would begin to soften up after about a year unless kept in a freezer.
I usually have some antimony in my alloy and the BHN numbers seem to hold up well even after 10-15 years.

Mike,
Following is Dan's results/comments several years ago.
Wayne
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Gents,

Here's a bit more detail about some alloys that have been tested for Brinell Hardness stability. The testing started just after returning from Raton 08. Each alloy tested was made from certified lead, tin and Lyman # 2 alloy. Considerable care was taken to make sure the testing was accurate and repeatable. Two other Brinell Hardness testers were used to calibrate the Lee tool that was used for the duration of the testing. All three tested the certified lead at BH 4.5, the tin at BH 5.0 and Lyman # 2 at 15.0. From these initial calibration tests I feel confident that the results I'm reporting are accurate and reflect the BH numbers properly. Some of the published BH numbers for lead-tin alloys is not accurate.

The testing, that lasted one year, was performed as follows:

First test was performed about 1 hour after casting the PP bullets for a given alloy.
For the first 24 hours the sample was tested every 6 hours.
For the next 6 days the alloy was tested every day at around noon.
For the next 51 weeks the alloy was tested every Monday at around noon.

Antimonial alloys tested:
Lyman # 2 (90/5.0/5.0) lead/tin/antimony
95.0 / 2.5 / 2.5
96.0 / 2.0 / 2.0
97.0 / 1.5 / 1.5
97.5 / 1.25 / 1.25
98.0 / 1.0 / 1.0

Lead-tin alloys tested:
20-1 & 16-1

One alloy was made with twice as much tin as antimony to determine what the stability characteristics are. That alloy was 97.0 % lead, 2.0 % tin and 1.0 % antimony. The alloy was very unstable. The takeaway from that alloy is don't mix an alloy with more tin than antimony.

The lead-tin alloys age-softened quickly. The 20-1 was completely age-softened 6 hours after casting and remained at that hardness, 7.8, for over a year. The 16-1 had a BH of 9.8 one hour after casting. At day 4 of the testing the BH was down to 8.2 and has remained at that hardness for over a year.

The moral of the story is binary alloys (i.e. lead and tin) don't change hardness over time. When you put the antimony in them, that's when they start doing crazy things with varying hardness. I just use 20-1 and don't worry about it.
Cody

I thought it was just the other way around in that the lead tin alloys were the ones that age softened in a years time unless kept in the freezer.
I have some water dropped WW's that are within 2 BHN numbers of when they were cast almost 20 years ago.

Nope, I'm right. Michael Rix has done quite a bit of experimenting on this, in addition to Dan Theodore's work. It is really amazing how the hardness of the alloys with antimony changes over time. I am not convinced it makes any different at silhouette ranges, but sure could at long range. I like to eliminate variables and just stick with 20-1.
Good luck, Cody

My alloy of approximately 50-50 WWs and pure lead to day at plus 30 hours measured 7.5 -8 BHN. I have no clue to the proportions of lead/tin/ antimony of this WW alloy.

Dave Scovill: "Alloys" and "Heat Treating Cast Bullets" 1990 The Handloaders' Bullet Making Annual, Wolfe Publishing Company.

Lintotype alloys with a trace of arsenic will harden over 60 to 90 days whereas pure tin:lead alloys will soften.

Hardening of linotype alloys can be done quicker by heat treating from 462 degrees to 485 degrees (15 degrees less than when the bullets become mushy) and then annealed at 190 degrees F.

Wheelweights:
Annealing time: Brinell Hardness
no annealing 30 to 31
15 minutes 29 to 30
30 minutes 27 to 28
60 minutes 24 to 25
105 minutes 21 to 22
120 minutes 19 to 20

Yeah, I though I remembered DT saying that was the reason to shoot up your yearly bullet quota as they would soften after a years time passes and that softening could be slowed down by storing them in a freezer.
I don't expect my current alloy to harden much over 8-9 BHN C scale but it will be interesting to track them out to 14 days or so.
I wonder if the water quench has a stabilizing effect on the alloys ?

The WW's have some antimony in them but I don't know for sure how much. Can't be very much when cut by half pure lead in my 20 lbs alloy melt.
If I understand this correctly the Tin alloys with lead but the Antimony mixes and forms a "tree" structure acting like an aggregate similar to what gravel does to strengthen concrete. The down side of antimony in an alloy it increased barrel leading.

Not if you paper patched.

KW

True, I've been doing some experimenting with PP antimony bullets in .303 this year and leading has not been an issue, now if I could only get them to stop key holing as my bullet diameter seems to be the real issue. I've been cutting mold cavities with incremental diameter changes at the base and shank to see if I can come up with an accurate bullet design in that caliber.
The greasers have shoot well with a gas check but it would be really fun to get the PP's to shoot well also.

You mean go got a Mark Smelly IV to shoot well with any projectile?

You ever hear of Guiness World Book of Records

Yeah,they can surprise you ! I think the # 5 jungle carbines are the only ones that are kind of temperamental to get to shoot.

FWIW, looking back, it was Dan T's tinkering with alloys that got me to try 1-16 lead tin mix when my then go to was 1-20 for 'long range'.

I shoot grease groove bullets in competition exclusively. Silhouette, midrange and long range.

For silhouette I just used whatever was in the spare pot, usually either 1-25 or 1-20, didn't seem to matter either way.

While I am not into the scientific realm, and do not want to go there for practicality's sake, I am interested in and pay attention to results.

With that said, for shooting paper and steel targets at 800 yards and beyond, I began to notice and then track my core groups on paper and I became of the realization that the 1-16 core groups did appear to be smaller, (tighter if you will), than 1-20 in my rifles with 16, 17 & 18 twist barrels. (As Dan suggested I may find.)

I also noticed that after switching to 1-16 my place ranking at matches began to go up to the point I was winning big matches. I added this last sentence so you will understand what I mean when I say, "I pay attention to results." Bottom line, it was the results on target that convinced me 1-16 makes a difference.

I seem to recall Dan got to 1-10 in his experimentation, I saw no difference with 1-14 and since I was happy with the results with 1-16 I just stayed there. Sort of a, "if it ain't broke, don't fix it," sort of thinking.

Hopefully I will see you at a match, soon.