Question about alloy, for smart casters!

[bigdog454]

If I have a ingot, lets say 2 lbs of lead alloy that is 9 bhn, how much alloy of 18 bhn would I add to get a alloy of 12 bhn? Also what is the formula that you would use to reach this goal?
Now I know that there are some very smart casters out there who have done this. would you please share. All casters are smart, some just know answers to problems that others have'nt solved yet.

[Calamity Jake]

Roughly 25-30% Your only trying to change it 3 BHN points, that's not very much and you can have that much error in the way you check hardness or your tester or both.

I add 25% Lino(20-22BHN) to my WW(9-12BHN) and get 15-17BHN after a 10 day to a 2 week wait from the time I make the alloy.

[runfiverun]

you add your #'s and divide by the amount.
like this 3%antimony and 7%antimony makes 10% divided by 2 ='s 5% antimony.
so your mathwould look like this 3=3=x.
if you know how much equals the final answer it's easy

[joeb33050]

you add your #'s and divide by the amount.
like this 3%antimony and 7%antimony makes 10% divided by 2 ='s 5% antimony.
so your mathwould look like this 3=3=x.
if you know how much equals the final answer it's easy
Nay. This averaging process is not true for many/most combinations of lead, tin and antimony. If I copied it correctly, here's the chart, from "Cast Bullets" by Col. Harrison. As you can see, the relationships are far from linear.
Now, the CBA forum has a workbook, incorrect, that allows one to incorrectly-most-of-the-ratios calculate BHN from percentages of constituents. The Web Meister either doesn't understand or hates scientific processes, and demands freedom to incorrectly calculate BHNs. Go there if you wish to be remarkably precise and frequently wrong.
joe b.

[fredj338]

Unless there is some reason for that exact precision, a 50/50 mix will get you close.

[HeavyMetal]

I think your going at this wrong.
you need to add the 9 bhn alloy to the 18 bhn alloy not the other way around!

Next question: is this theoritcal or are you trying to make a 12 bhn alloy for a specific reason/ caliber?

If for a specific caliber/ pressure there is not much difference between 9 bhn and 12 bhn which might be a tougher target to hit than you think.


I might just stay with the 9 bhn and load a little lighter or, if possible, load the 18 bhn hotter.

Please advise caliber / load.

[southpaw]

Lets give this a try: [(2lb) 9bhn + (1lb) 18bhn] / 3lb = 12
If you multiple the lbs. by the bhn then add them and divide by the total number of lbs. this should give you the ending bhn.

The chart does make sense even tho I cant figure it out.... The different make up ( tin, antimony ) would affect the hardness. I would try 2-1(or less of the 18) then test it after a couple days and see what that puts you at. If you need to add more of the 18 bhn to bring it then do so. If it is too high then you could add a little pure to bring it back down.
Just my thoughts.

Good luck

Jerry Jr.

[John Boy]

65% of the Bhn 9 and 35% of the Bhn 18

[imashooter2]

A better picture of the chart:

http://home.comcast.net/~imashooter2/pictures/fig8-sm.JPG

[southpaw]

Well that clears up the chart thing. Now if there was a easy way of telling what the makeup is of our unknow allows....

[bigdog454]

Soutpaw, you hit the nail on the head! I don't know the percentage of the alloy, but I can test (relatively) the hardness, (BNH). Looking at the chart of shooter2, tells me that I would be right in assuming that using a straight line approach to hardness (averaging) won't give me accurate results. I think that alloying lead of an unknown percentage of the original alloy must be more art then science at the casters level, as I can not analize, the originating alloy.
using the information that your great minds have provided, I will try to reach my goal of 12 to 14 bnh. I wll be trying the mix in different handguns, from 38 special, which is not a problem, to using it in my 454 and the ruger 30 carbine revolver which has been giving me fits with lead bullet.
once again thanks to all, and any further ideas or comments are more then welcome.
BD