Recipes

Table 1

Table 2

Conversion Factors

Table 3

       Super Hard is a 70% lead (Pb), 30% antimony (Sb) alloy that is used to increase the antimony percentage (harden the alloy) of your current lead supply such as clip-on and stick-on (tape type) wheel weight, plumbers lead, sheet lead and many other lead alloys. It is made with virgin metals, not from scrap metals so you are adding perfectly "clean", new alloy to your casting pot. With the addition of pure bar tin from Roto Metals the sky is the limit and you take control of your casting alloys, even with many scrap lead alloys.

       Antimony (Sb). It is the current metal used to strengthen/harden lead alloys for bullet casters and for numerous applications in the metals industry. It is an extremely brittle metal but has unique characteristics in a lead alloy in addition to its basic hardening, such as the ability to heat treat a lead alloy bringing the final hardness up far more than what the percentage of antimony would suggest. Alloys such as monotype (19% Sb) and stereotype (23% Sb) are so brittle because of their extremely high Sb percentages, bullets cast of them can actually break in two by simply chambering a round or dropping it on a cement floor. Antimony is a valuable part of the bullet casters alloy but too much of a good thing is clearly not a good thing. Super Hard is for blending (alloying) with softer lead or lead alloys, never try to cast bullets with Super Hard alone, you will not be a happy camper.

       Antimony is a silver white metal, very hard and very brittle. It has no characteristic crystallographic surfaces when sheared. Melting temperature is 1167° ^F and even when melted at or above that temperature it is not easy to get a homogeneous alloy with lead. In addition, Sb in it's pure or powdered form is highly toxic and proper breathing apparatus and proper and thorough clean up afterwards is necessary. So what to do? Antimony is an important part of many bullet casting alloys but it's both difficult and could even be dangerous to try to alloy yourself. Here is one of the real services provided by Roto Metals, the professionals have done the difficult and dangerous part of alloying Pb/Sb for you. Super Hard melts at about 650^{o F}, is homogeneous with your base alloy and thus blends in with your melt quickly and easily with your final flux before casting.

       Weight and Size differences. As the percentages of the alloys in a melt change other changes occur in addition to the weight of the bullet. In general the higher the percentage of Sb the larger the as cast diameter of the bullet and the larger the diameter of the bullet the more increase there is. In other words a 45 caliber bullet will show more of an increase than a .308" caliber bullet (table 3). In addition, the alloy percentages have a direct effect on the final sized diameter (table 1). I imagine the sizer die makers get daily phone calls from customers complaining (as an example) that their .309" die sizes to .3084" and not .309". If you change the alloy the weight, as cast diameter, shrinkage, sized diameter and BHN all change. Higher Sb percentages also result in less shrinkage as the bullet cools and it's possible for this simple fact to result in bullets that are a bit tougher to get to fall from the mold (table 2). From the tables it can also be seen that in reverse the softer the alloy (less Sb) and the larger the diameter of the bullet that more shrinkage will occur.

       Sb and Brittleness. As you have already read, raising the Sb percentage makes bullets brittle so the key is to not get carried away, your intended target should guide you to the maximum percent of Sb in an alloy. Look over the recipes I listed below and you'll notice that in only Hardball (6% Sb) and Lyman #2 (5% Sb) and 1 other (Alloy #2-1) did I go over 5% Sb and #2-1 is still under 5.5%. The vast majority of smokeless powder handgun and rifle loads should be well served with these Sb percentages. Hollow points intended for hunting/expansion should be about 2% Sb and 2% Sn. Thanks to Super Hard this is now fairly easy to dial in.

       The tin (Sn) in your melt. Sb oxidizes rapidly when in contact with air and the Sn in your melt helps inhibit this oxidation in melts up to about 750 degrees. With higher temps than this tin itself oxidizes much more rapidly and looses much of it's ability to inhibit Sb and Pb oxidation. It's not only the surface of the top of the melt in your pot that's in contact with air but also the stream of alloy from a bottom pour pot or even from a ladle that Sb will also oxidize, the hotter the alloy the faster the oxidation. This stream of alloy into your mold is where tin will play it's most effective roll in reducing the oxidation of Sb. By reducing the oxidation of both Sb/Pb tin reduces the surface tension of the melted alloy which enables your alloy to fill in the smallest corners and angles inside the mold resulting in well filled out bullets. The addition of 1 or 2% Sn is very beneficial when adding Sb to your alloy.

Super Hard / WW Recipes

(Where no as cast weight or BHN given alloy not yet blended)

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Notes, conclusions & surprises

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Notes & conclusions on alloys 3 and 4: < Go to alloys 3 & 4 >

Abbreviations

CWW

SWW

WW

SH

lb

BHN

HT

Gr.

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Roto Metals Super Hard = 70% Pb - 30% Sb / 1lb Super Hard = 4900 Gr Pb / 2100 Gr Sb.

There is only one place you can order Super Hard