Adding Tin to Bullet Metal
Lead in its pure form is really not suitable for making bullets for most cartridge firearms. It is too soft and tends not to cast a well defined bullet.
To cast a good bullet, lead must be mixed with or alloyed with some amount of tin. Tin can reduce the melting point of the alloy but its primary value is reducing the surface tension of the alloy, allowing the metal to fill the mold properly. To a certain degree tin will add hardeness to the alloy. Unfortunately tin is an expensive metal, generally costing more than 10 times the same weight of lead, to increase the hardness of bullet alloy, antimony is often used. While the addition of antimony reduces the amount of tin required to make a good bullet alloy, some tin will still be needed.
If you can find it cheap at a yard sale or otherwise scrounge it, 95/5 solder (95% tin /5% antimony) is an ideal material for adding tin to an alloy. Almost pure tin, it is used primarily by pipe fitters and has been purchased in error by many a weekend handy-man who finds that its melting point is too high to flow properly using an ordinary propane torch. I also have used other lead free solders in bullet alloys.
Oatey Safe Flo silver bearing solder is made mostly of tin it is alloyed with less than 1% silver and a small amount of bismuth and copper.
FryFlo 97 is 97% tin and 3% copper. Copper in small quantities can help to harden bullet alloys but its high melting point generally precludes its use by the home caster.
In times past, I have also used lead containing electrical and plumbing solder which usually are 60 parts of lead to 40 parts of tin.
Another source of tin that you might happen upon is wiping or bar solder, made of 37 percent tin/63 percent lead. Wiping solder was once commonly used by the phone company and electricians to seal and connect lead conduit.
Bullet Lubes and Sizing
Cast bullets must be lubricated and may need to be sized before being loaded into a cartridge case.
Without proper lubrication, friction between the barrel and bullet will cause lead fouling to collect in the rifling, destroying accuracy until the leading is cleaned out. Most cast bullet designs will incorporate one or more lubrication grooves near the base of the bullet to contain these specially formulated lubricants.
For the most part I use Lee Liquid Alox thinned with a small amount of mineral spirts to the consistency of good quality pancake syrup. The directions on the bottle suggest coating the whole bullet in lubricant by tumbling it in plastic container with liquid alox. I find that to be a rather wasteful practice. The method of application that I use is to hold the bullet so that its axis is parallel to the floor. I use a cut down popsicle stick to apply a few drops the thinned Alox to the lubrication grooves of the bullet and turn the bullet on its axis so that the lubricant will be distributed evenly in the grooves. The bullets are then placed base down on wax paper to dry overnight.
A cast bullet sizing tool that you may encounter is the Lee bullet sizer and punch. No longer in production, it is simply a steel cylinder marked with sizing diameter. Slow but it works, I have used them for years.
The Lee Sizing kit is designed to be used with a metallic loading press. It is an improvement over the old system but you do need a reloading press to use it.
I currently use both types of bullet sizing tools for different bullet diameters.
Scrounging Material for Casting Bullets
As printing and automotive industries have transitioned from using lead for other materials, cheap bullet metal is becoming increasingly hard to find, though not impossible.
From l-r Linotype, clip on lead wheel weights, lead bullets recovered from backstop.
Lead Wheel weights made of a lead/antimony alloy have been used to balance automobile tires many decades. There are two types of lead wheel weights, the most common uses a steel clip to fasten the weight to the wheel rim. The alloy used can vary widely but generally it will contain about 3 percent antimony, less than 1/2 percent tin and perhaps a 1/4 percent of arsenic and the rest lead. On its own, alloy recovered from clip on wheel weights can make an acceptable bullet but a little tin added to the mixture will improve the alloy greatly. The second type of lead wheel weight comes in the form of a strip of metal that is scored in order to allow the appropriate amount of weight to be broken off of the strip. Double side tape is used to secure the weight to the tire rim. The alloy used for this type of wheel weight is very soft and may contain less than one percent of either antimony or tin. It is extremely soft. I pick wheel weights off the street with surprising frequency however steel and zinc weights are starting to replace the use of lead. All lead weights are easily scratched with a knife. If a wheel weight is hard then it is made of zinc or steel and so should be discarded.
I have heard many people suggest obtaining used weights from tire shops. Be careful that the person that gives them to you is authorized to do so and that there is enough lead in the bucket to make it worthwhile.
Range scrap refers to bullets, shotgun pellets and other lead containing projectiles recovered from backstop of a firing range. The alloy composition of range scrap can vary widely depending on the type of ammunition fired into the backstop.
I avoid salvaging lead from jacketed bullets as I have found that when jacketed bullets are added to molten lead, any air trapped between the jacket and the bullet core can cause them to splatter lead seconds after they are added to the pot. Also many jacketed pistol bullets manufactured for use in indoor ranges enclose the lead core entirely. Copper will not melt at the temperatures produced by your average electric melter. The means that the jacket must be cut or broken open before adding to the pot otherwise you will just have a sealed copper pouch full of molten lead. Bullets plated with copper are a different matter, all that is required is a whack with a hammer to crack the plating before adding them to the pot. This will allow the lead to flow out through the cracks when it melts, the copper plating will then float to the top to be skimmed off. As it happens, often the rifling of the gun in which these bullets have been fired will have cut through the thin layer of copper making it unnecessary to crack the plating.
Most range scrap will have a sufficient amount of antimony to harden the bullets due to the common use of commercially swaged pistol bullets, however the alloy will likely be improved by the addition of a small amount of tin. The tin will help to reduce barrel leading by coating the antimony crystals that form on the outside of the bullet as well as helping to fill the mold out properly. Usually I will add a few pieces of linotype or a couple of feet of wire solder to a ten pound pot of alloy.
Lead bird shot scavenged from a shotgun range will contain from 1/2 to 6 percent antimony and virtually no tin. For the most part it is really is too soft cast good bullets on its own. Some tin and perhaps some antimony will have to be added to cast a good bullet that will not lead excessively.
Made obsolete by laser printers and modern production printing methods, linotype printing has all but disappeared. Still this material crops up now and then.
In general formula, linotype alloy is composed by weight of about 4 percent tin, 11 to 12 percent antimony and the rest lead.
4 Sn 12 Sb 84 Pb
Be very leary of anyone selling ingots of linotype. Due to its tin content, linotype alloy often commands a fairly high price so there is a great temptation for some people to misrepresent wheel weight alloy or other lesser quality metal scrap as being more than it is.
Most plumbing lead is soft and will be close to pure. Lead pipe generally is near pure lead but it may have a fraction of a percent of antimony and or tin.
At one time lead pipe was in common use for water supply lines in much of the United States. Even today there are still thousands of homes which still have lead service lines, a possible source of scrap lead when the service lines are replaced. Plumbers lead has also be used to cap the soil pipe to the sewer line in older homes.