A Method of Determining The Percentage of Linotype

In this article I will show you how you can determine the percentage of antimony and the BHN for cast bullets using your mould and powder scale. It consists of casting bullets with your unknown antimony content, weighing your bullets and dividing the weight of your bullets by the weight of a bullet of refined lead in the same mould hole. You then compare your ratio with the ratios in the data sheet and read what your BHN is. By refined lead, I mean lead that is melted at 850°F and let stand. After one hour, scrape off the slag – do not flux it. Scrape the slag off every hour for six hours and you will have burned off most contaminates. Do not do this with battery plates! Battery plates have calcium in them and upon melting they put out a Pb-Ca product that when combined with water gives off a poisonous gas.

A couple of years ago I was melting down some range-scrap lead bullets and I assumed they were mostly wheel weights and their BHN would be 13. After a month or six weeks had passed from casting up a bunch of bullets from this range-scrap, I used my home-made BHN tester to test them and they had a BHN of 15. I wondered how high the antimony content was and I began a futile search to find out. I could not find very much on linotype-lead alloys. So, I figured I’d do a little investigation on my own. I bought some new linotype that was guaranteed to be 12% antimony by the chemistry lab at New Mexico Bureau of Mines and Resources in Socorro, New Mexico. I worked out a formula to find out how much lead I would have to add to a pound of linotype to get a specimen from 12% to 1% antimony. This was a very inconvenient way to do it. I got some figures and checked them out by running the experiment three times. I then had data on one mould but that was all I had.

Then my wife introduced me to "The Web"! I wasted many hours "surfing the web" to find confirmation of my data. No luck until I hit upon www.welcocastings.com . It is from the Welco Castings of 2 Hill Yard Street, Hamilton, Ontario, Canada. Oh, joy Devine! They have a printout entitled: Physical Properties of Cast Lead-Antimony Alloys. In this printout they have a column Density, which is the specific gravities for 0% to 14% antimony, and so on. As I saw this Specific Gravity (Sp.Gr.) of 0% antimony (lead) at 11.35, I knew I had hit pay dirt. Now, I don’t agree with their BHN for antimony percentages, but I could see a correlation. I divided the Sp.Gr. of 1% antimony with the Sp.Gr. of lead, i.e. 11.26 divided by 11.35 equals 0.9921. I then divided my sample weight for 1% antimony by my sample weight for lead. I used only the front hole to cast all my specimens. 182.55/183.09=0.9971. BINGO! Although not exact, it will get you into the ballpark and I christened my data Pseudo Specific Gravity (PSG).

I then went to work. I bought twenty-five pounds of fresh, virginal 12% antimony from a very good friend, selected four moulds and started marathon casting and weighing.

The four moulds are: 180 grains LBT (the best mould I have ever used in my 55 years of bullet casting), a Lachmiller 358-150 (this mould is so old that it doesn’t have vent lines but it is the most consistent in bullet weight you could ask for), an RCBS 35-200 FN ( a fairly good mound), and an RCBS 37-250 FN (this mould has Morris type grease grooves and is a very fractious mould to use).

The only thing more boring than weighing bullets or watching mud dry and crack is reading someone else’s rough data. Suffice it to say: Every data point I produced consisted of the average of three samples of at least 10 bullets. I then listed the lowest PSG, the highest PSG, and the average PSG of the four mounds. In the next to last column on the data page, I subtracted the ratio of (Welco Sp.Gr./Average PSG) from 1 to show how close I came to Welco Sp.Gr. In one case, the data for 4%, my data was 1.9% lower than Welco’s. For the 3% and 9% data, my data is 1.1% higher than Welco’s data. The rest of my data runs from 2 tenths of 1% to 8 tenths of 1% higher than Welco’s. Pretty darn close! The BHN is in the last column.

Data Sheet for Linotype-Lead Alloys - By Tom Cost

% Antimony	Welco Sp.Gr.	Highest PSG	Lowest PSG	Avg. PSG	1-(WelcoSpGr/	BHN
					Avg. PSG)

1%	0.9921	0.9981	0.9938	0.9965	0.0040	6.50
2%	0.9850	0.9968	0.9925	0.9940	0.0060	8.90
3%	0.9880	0.9896	0.9884	0.9888	0.0110	13.00
4%	0.9718	0.9839	0.9771	0.9808	0.0190	13.9-14
5%	0.9648	0.9746	0.9695	0.9728	0.0080	14.7-15
6%	0.9586	0.9626	0.9548	0.9604	0.0020	16.00
7%	0.9524	0.9616	0.9538	0.9572	0.0050	16.50
8%	0.9463	0.9533	0.9441	0.9505	0.0040	17.60
9%	0.9342	0.9467	0.9442	0.9450	0.0110	18.70
10%	0.9330	0.9365	0.9348	0.9349	0.0020	20.00
11%	0.9269	0.9307	0.9286	0.9293	0.0030	21.00
12%	0.9207	0.9282	0.9232	0.9258	0.0080	22.00

Between the time I finished my first experiment and logged on to Welco’s Internet site, I remembered an article by Ken Mollohan in an old issue of The Fouling Shot (July-August 1988) which is the forerunner of The Cast Bullet. Published by the Cast Bullet Association, this article "Alloying Guide" appearing on page 74-19 is a godsend for all cast bulleteers and I used it to figure my percent of antimony. Since it is copywrited I cannot put it out on the Web. A copy of The Fouling Shot – Issue 74 – July-August-1988 is available from Mr. Stanley Livingston, PO Box 412, Oquawka, Illinois 61469 for $4.50.

If anyone wants to discuss alloying lead-linotype, casting or similar interests they can get me on e-mail at: thebulletcaster@qwest.net

Don’t sent jokes or any other irrelevant stuff. If you use these data in any written article or on the Web, please acknowledge the author. I am very vain. Do log onto: www.welcocastings.com . It will be quite reveal-lee-ing when you see their moulds.