25:1 lead/tin. What Brinell.?

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  • Last Post 16 September 2015
Singleshot S.A. posted this 12 September 2015

Can anyone please tell me what BHN, 25:1 lead / tin would be. After reading the Richard Lee MODERN RELOADING and comparing the scale in Lymans Cast Bullet I am a little confused. I have a new LEE lead hardness tester, and seem to get along OK with it, if I have a few drinks first to steady the hands. ;) I have some alloy that I made up that measures .078 with the hardness tester,  which is BHN of 8.2 according to my Lee book, but I can't find a comparison for it anywhere. Is that near 25: 1 or 30:1.? Linotype and Antimony are hard to come by around these parts, so I'm hoping to find a good alloy mix with just pure Lead and Tin. If 11 BHN = 16:1,...10 BHN = 20:1,...what does 9 BHN = AND what should it measure on the tester. Better still, what measurement should I be looking for to achieve 25:1 and 30:1 ?

All help and advice is always appreciated, cheers S/S S.A.

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onondaga posted this 12 September 2015

http://castbulletassoc.org/view_user.php?id=9226>Singleshot S.A.

Here is how to answer that for yourself:

Basic Rules for Hardening Lead-

For every 1% additional tin, Brinell hardness increases 0.3. For every 1% additional antimony, Brinell hardness increases 0.9. For a simple equation, Brinell = 8.60 + ( 0.29 * Tin ) + ( 0.92 * Antimony )

You see that at the bottom of every page on the RotoMetals site, it gets asked a lot.

I have the Lee Hardness Test Kit also and am completely happy with it.

Do be aware that: how any lead sample was cooled can dramatically effect hardness test results. You may have to reheat samples and let them cool gently of their own accord to get accurate hardness test results that will match what the formula says.

Knowing your alloy content and using the formula correctly is actually more accurate than the test kit if your alloy was slowly cooled correctly.

If you wish to plot the error of your tool, use the tool on a correctly cooled  certified alloy sample to calibrate error. The Lee tool errors very slightly high in test comparison results compared to laboratory grade test results. Gary

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Ken Campbell Iowa posted this 12 September 2015

just a comment based on my own experience ... i have shot mostly scrap ... unknown alloy, but for years i did shoot exclusively taracorp magnum ... at my plinker-level of acceptable accuracy ( 2 to 3 moa up to 100 yards ?) ... from a time when i shot only 22 rf backstop lead thru my exquisite taracorp period to my now :: ” looks-like-lead ” alloys, the bottom line was/is that my goals of 2 to 3 moa and velocities up to 1800 .... seem to be met with a very wide range of alloys ..... the alloy in my experience is maybe 10 per cent of whatever is keeping us above the 2 moa barrier .

that said, i do keep bullets from different pours separated and labeled .

here is what i think ( always dangerous ) i know about bullet alloy vs. accuracy .

1) jackkt bullets can be very accurate, so it is easy to figure that harder alloys will be more accurate . ken sez:: maybe once you get everything else right, and you are under 1 moa all the time ... alloy probably becomes a bigger factor . but if you are at 3 moa, you won't solve the big mystery by changing alloy 2 brinell numbers .

2) weight errors due to different alloys : ken sez: at 100 yards, this will be nearly insignificant in a 2-3 moa group.

3) initial bullet resistance at ignition thus different pressures :: ken sez:: this one has some significance if a wide hardness number exists, but 2 or 3 numbers may not show up at the target . i think all lead up to brinell 20 or so is so soft it just doesn't matter .

4) lastly, remember the lowly 22 rimfire; shooting nearly dead soft lead ... and getting under 1/3 moa groups ... food for thought there ... i am never sure what those rimfires are trying to tell us ... my federal champion 22 rf in my nearly stock 10-22 shoots better than my 243 win. with nei cast in my rem 700 tuned varmit wt. lapped y pillar bedded pride and joy . doesn't seem right .

just some thoughts, more data points floating on a graph ...

oh, what i think makes small groups ?? :: it is really the chamber and barrel quality .... not a magic bullet mold or magic lube or a magic alloy ..... dangit !! how boring .

but my 2.5 moa plinking loads from about any mold in about any gun still gives me a whole lot of enjoyment ... FUN to you country boys .... nothing better than a mouse-sized hole in a bean can from a 38-55 ... in the morning ... dang !! NOT BORING !!

ken

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onondaga posted this 12 September 2015

http://castbulletassoc.org/view_user.php?id=9226>Singleshot S.A.

You state you want to “achieve 25:1 and 30:1". Checking hardness to check or verify that you have those alloys is only as accurate as your mix and your measuring tool. In actuality, simply using 25 parts or 30 parts certified pure lead and 1 part certified pure tin gives you exactly what you want regardless of what your measuring tool says.

I gave up on hit and miss alloys years ago because I was looking for accurate standards that don't change from batch to batch. You are only going to do that with certified pure metals or certified alloys.

Yes, I use a inexpensive recreational alloy too, it is 50% soft range scrap and 50% Linotype scrap and consistently checks at BHN 15 for me with my Lee tool. That alloy impacts the same POI for me as certified Lyman #2 Alloy but I DON'T use the recreational alloy for hunting. I use Certified Lyman #2 alloy for hunting.

Good sources for certified pure Lead, Tin, Antimony and certified bullet alloys at competitive prices are:

http://www.rotometals.com/Bullet-Casting-Alloys-s/5.htm>http://www.rotometals.com/Bullet-Casting-Alloys-s/5.htm

and

http://www.zipmetals.com/Bullet-Casting-Metals_c_44.html>http://www.zipmetals.com/Bullet-Casting-Metalsc44.html

Gary

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Lee Wiggins posted this 13 September 2015

Singleshot, At the bottom of the site home page, click on downloads then alloy calculator.Using it you can get the BHN for any alloy we play with. Lee Wiggins

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bigbore52 posted this 13 September 2015

Singleshot S.A.

If I could add my two bobs worth, you may be looking at this from a different angle with trying to work out your metal ratios in the brew hardness - I agree with all that's been posted but would suggest that your method of casting can vary the result along with the ingredients which you may think are 'pure' wheel weights etc.

I now only cast with 100% pure lead and tin in a ratio of 20:1 - then drop from the mould into cold water....I don't have a hardness tester anymore as found them inaccurate early on and now they are hard for me to read B)...maybe they've improved some, unlike me? so every now and then I send a few casts off to a lab for professional analysis, - last lot all came in at 14.5BHN - variation of 0.35BHN over 25 different bullets from three different casting sessions in a month..I haven't sent some for analysis that were not water dropped so I have no idea what effect that has other than that's my process and what I do..but importantly I used the same process and known pure metal ratio for each casting session. I mention that not to say you can do it and get the same result, but to illustrate that I believe consistency is a big point often overlooked. That consistency also extends to the composition of the metals you use

I would suggest the 'secret' if you want to call it that, is to start from scratch, use the one method or process your happy with and only pure metals first up - then keep that as your benchmark.

So if you change the brew or any other process, then at least you have a fall back and know what you can get with pure metals - I've found, wheel weights and other “commercial” boolit brews do vary considerably from what they are supposed to be made from - that raises all sorts of issues and gives us casters unnecessary headaches including inconsistent accuracy.

I gave up using them or scrounging other materials solely because of that - By purchasing the pure metals from a supplier, granted, there's a cost alright and it may not suit lots of casters and likewise making it up themselves - but not being related to The Lone ranger or having my own silver mine, at least I know that's one less variable to worry about in achieving the desired BHN.

I know some casters and clubs who buy bulk and split the costs because they too have found inconsistencies with wheel weights or other sources etc....maybe that's an option worth considering for you?

Hope that helps.....

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Singleshot S.A. posted this 15 September 2015

Thanks again Gary and Ken, Lee, that is a great format. bigbore, I understand what your saying, thanks.

I'm not new to casting, just new to getting serious about it. I've only ever played around at 50 - 100 yds, done ok, but now want to double that, then go again.

I only ever use pure lead (plumbers flashing), never bothered with reclaimed stuff because I can get flashing at any time and I use Pewter mugs etc from the junk shops for my Tin.

No one answered the original question though, What measurement on the LEE tester is 25:1 or 30:1. ??

Thanks guys,S/S S.A.

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onondaga posted this 15 September 2015

http://castbulletassoc.org/view_user.php?id=9226>Singleshot S.A. ” What measurement on the LEE tester is 25:1 or 30:1. ??"

30:1 is about BHN 9 according to RotoMetals certified specification

25:1 is about BHN 9 according to RotoMetals certified specification

If you are wondering why they both are about BHN 9, that is easy to understand. Tin has little effect on the hardness of bullet alloys when they are so close in Tin content and no Antimony is present.

Your Lee Hardness test should show a 0.097” imprint size for BHN 9.  You should not be able to tell the difference between 25:1 and 30:1 through the use of your Lee Hardness Test Kit.

That is not the answer you wanted if you want use your tool to tell the difference between  30:1 and 25:1 but that is the metallurgy of the answer. So, If you want to assign a 25:1 or a 30:1 description of your unknown alloy of scrap roofing lead and Pewter scrap, the Lee tool does not do that. It will tell you .097” or BHN 9 for both.

Gary

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Singleshot S.A. posted this 16 September 2015

That's the answer (.097) I was looking for Gary, thanks.

I tried some 30:1 in the 38/55 because my little Saeco mold (200g) is a fraction small at.380, which is groove depth on mine. Hoping the softer mix might 'upset'a bit. I think it did work. The group was certainly better. Have sauced better molds so it was just a bit of fun testing.

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