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BHN formula?  Rating:  Rating
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 Posted: Mon May 5th, 2008 04:24 pm
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largecaliberman
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To all Bullet Casters out there,

I have collected Linotype, 60/40's, range lead and even antinomy and I want to mix some of my metals to get the desired BHN.  My question is, is there a mathematical formula I can use?  I want to take a more scientific approach.

 

Thanks :dude: in advance.

;}

 

 



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 Posted: Mon May 5th, 2008 05:30 pm
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giorgio de galleani
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Not knowing the exact composition of the various  scrap alloys you have ,a scientifical approach is rather difficult,.as they change from one batch to he next.

And then you must decide what hardness do you want ,and at what pressure are your loads.

I'll give you my unscientifical habits, please let me know  how hou do ,with your loads.

I shoot mostly cow boy loads is sa pistols and pistol caliber lever actions.

I shoot rifle loads around 1500 fps ,with gas checks,in modern bolt actions and single shots.

In all of the above I merrily shoot range pick up lead that passes the thumbnail test ,air cooled.

When I used to shoot 308 w loads that cycled my M14 at 300 meters, I used water quenched Wheel weights.at 1800-1900 fps

Gas check  major factor 9x21 loads liked Lyno and gas checks.45 ACP goes well with  the usual soft  range scrap,as 30WCF marlin microgrooves,as long as I use low pressure loads.

In my 45/70 marlin guide,soft lead does not lead(pun intended)as long  as I am able to survive the recoil.I

You might get you an LBT hardness tester. To be a little more scientific than me.

An old Wolfe Publishing book  on Cast Bullets contained a lot of formulas on alloys and hardness,but I was unable to understand them ,and I humbly believe they were practically meaningless.



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 Posted: Mon May 5th, 2008 06:26 pm
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runfiverun
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i just base what i want on the 100 lb rule

 as in 3% = 3lbs etc. ..and put enough stuff together to melt in my big pot

that holds 100 lbs.

other than that 3-4% ant and 1% tin will get me to 15-1600 fps with or without g/c

7mm and up in rifle 6%antimony and 4% tin with g/c will get me to 2300.

smaller rifle stuff should be harder.

as should the stuff for your semi-auto's be a different alloy.

in pistols i use the 1-4 mix some pistols want a bit harder mix so the 4/6

works here also.

4/6 is made with 1 part lino and two parts wheel weights and tin 3lbs per 100 wt.

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 Posted: Tue May 6th, 2008 12:37 am
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454PB
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Since scrap lead, range recovered lead, and even linotype can vary so much, using a hardness tester is the best way to arrive at a certain constant BHN.

 

Personally, I don't worry about it much. Good castability and the desired accuracy is more important than the BHN. In the past, we were told that an alloy had to be a certain hardness to shoot well at a certain velocity. I (and a lot of other casters) have learned that hardness is just one component to success with cast bullets. I didn't even own a hardness tester until around two years ago, and had good results without knowing what the BHN of each alloy was. Hardness testers are fun and interesting, but a good micrometer is far more important to me.

 

Here is a great web site for calculating alloys:   http://www.lasc.us/CastBulletNotes.htm

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 Posted: Tue May 13th, 2008 03:29 pm
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largecaliberman
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I was doing some "Spring Cleaning" and I came across this formula that I probably got over one of the shooting forums a while ago.  This formula is to determine how many pounds of lead needs to be added to 10 lbs of linotype to get a 14BHN or any BHN.;}

 

7x + 22(10) = 14(x+10)

 

7   - BHN of lead

22 – BHN of linotype

[size=14 -  ]Desired BHN

10 – 10 lbs of linotype

 

Therefore:

 

     7x + 220 = 14x + 140

 -14x  - 220   - 7x   - 220

  -7x             =        - 80     

 

  x= -7/-80   x= 11.4

 

Before mixing the metals, I tested each sample on a Lee tester.

 

I tried this on a small scale in a test tube (1lb linotype mixed with 1.14 lb lead) and the BHN, water quenched resulted around 12.4BHN on a Lee tester (the sample was molded into a Lyman 50 caliber mold).  After a week, I tested the same sample and the BHN came to around 14.6BHN.

 

The lead came from an indoor shooting range. 

 

I don't know the exact composition of  each metal so I relied on my trusty Lee tester.

 

Perhaps, someone could run the same experiment and it would be interesting to find out results from various lead slingers.  :lovecast:



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 Posted: Tue May 13th, 2008 03:53 pm
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jhalcott
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Another vote for LASC

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

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