Harry O
02-12-2013, 01:21 PM
I have been reloading for a little over 50 years, but have only been casting for about half that time. Over the years, I have developed some informal rules about casting that have cut down on my failures considerably. By using these rules, I can develop an accurate cast bullet load very quickly with very little experimentation. Every time I break these rules, I have more problems to work out before getting an accurate load. Here are the rules that work for me:
1. I use cast lead, plain-base bullets up to about 20,000-22,000psi chamber pressures (check the reloading manuals for pressures).
2. I use cast lead, gas-check bullets from there up to about 35,000-37,000psi.
3. I use jacketed bullets with pressures from there on up.
4. I have four ingredients that are used for the casting mix. They are:
a. Soft lead at Bhn 5 from salvaged roof sheeting (about 1,100lbs).
b. Wheelweights from large trucks & trailers at Bhn 11 (300lbs).
c. Monotype at Bhn 28 (200lbs).
d. Tin in either pure sticks or (mostly) in 50/50 or 63/37 solder (40-50lbs).
5. I have a bunch of recipes on the wall of my casting room that tell me how much of each material is needed to get a mixture of whatever Bhn I want for the bullet.
6. I air-drop almost all of my bullets onto a towel. Cooling speed affects hardness greatly. The weight of the bullet affects cooling. With bullets using the same melt and air dropped the same, a 100gr bullet will be about 1 Bhn harder than a 200gr bullet, which will be about 1 Bhn harder than a 400gr bullet. Dropping the bullet into cold water is another thing altogether and I have not done much of it.
7. I try to match the chamber pressure to the strength (hardness) of the bullet: ie, Chamber Pressure divided by 1,422 to get the desired Bhn to use for whatever plain-base bullet I am using. That means I stop at about Bhn 15-15.5 for them. I know there is a lot of criticism of this formula around here, but when I use it, I have very few problems. The more I exceed this limit, the more problems I have. In the past, I had to spend a lot of time working out the problems (due to exceeding the limit) and decided it was a waste of time not to use the formula.
8. I use Bhn 15 from then upward for gas-check bullets. That may be a bit lazy. I have seen some indications that I could probably go back down on the Bhn when I first go above 22,000psi with a gascheck and work it up to Bhn 15 by the time I get to 37,000psi. I have not experimented with that, though.
9. I use different temperatures for different moulds and mixtures (the more complicated the mould shape – such as hollow-base – and the more antimony, the more heat that is needed), but I seem to run my mix hotter than a lot of people here indicate they do. That means I cast slower than some people here claim, but it is worth it to me. From my tests, a hotter mixture has less variation in weight than cooler mixtures. I use Boric Acid to cover (protect) the top of the melt rather than fluxing constantly (this is with a bottom pour furnace).
10. I have had more problems with a melt that is too cool than with a melt that is too hot. Frosted bullets shoot just as well as shiny bullets even though they might not look as pretty. The only problem with high heat is when a bullet is partially frosted (especially a long rifle bullet). A partially frosted bullet is not usually straight. The major problem with high heat is when someone strikes off the sprue plate too soon. I am not advocating too high a heat here. Excess heat slows everything down, but otherwise, it is not the kiss-of-death some here have claimed.
11. I get as large a glob of melt as I can on the sprue plate (before it runs off the side). I expect it to stay molten several seconds before it flashes over. During that time, a dimple should form over the sprue plate hole. If there is no dimple, there will be much more variation in weight. I never do anything to speed the flashover (such as putting a fan on it or a damp cloth). I want the melt to dimple and that takes a little time. I am not saying anything against those who do accelerate the sprue cooling, but it doesn’t work for me.
12. Tin is a wetting agent and makes any mould cast better. Antimony is an anti-wetting agent (or clotting agent) and makes any mould harder to cast with. If I have problems when casting with a mould, I add heat progressively until I can cast easily or the pot will not get any hotter. If there are still problems (pretty rare), I will start adding tin until the problem goes away.
13. I normally use a minimum of about 2% of tin in the melt (one oz of tin to 3lbs of soft lead). If I am using antimony, I use a minimum of 2% of tin, but try to keep the amount of tin approximately equal to the amount of antimony. Some people here use 1/2 of the amount of tin than they use of antimony (or less). That can be done, but it is more difficult to cast with (more rejects). Besides, using more antimony than tin makes the bullet more brittle.
14. I start out with bullets sized 0.001” over the slugged bore size. With guns that are properly sized (chamber, throat, and barrel), that usually works fine. It the chamber or throat is larger than the barrel, I usually go to the largest bullet that will chamber easily. The bullet squeezes down in the forcing cone, but is still more accurate than if the bullet is sized for the barrel (but undersized for the chamber/throat). If the chamber or throat is much smaller than the barrel, I usually go to soft bullets sized to fit the chamber with a small amount of fast powder (light loads). This is to “bump up” the bullet and is the hardest combination to get to shoot well.
15. I have tried several types of bullet lube, but have brought them down to three: SPG for anything under about 800-850fps (for both Black Power and Smokeless). Tamarack (NRA 50/50 formula) for just about anything over that speed. If I have problems with the Tamarack lube (usually when pushing the maximum pressures listed above, particularly in rifles), I put a little Lee Liquid Alox over the bullet and the Tamarack. It is double lubed. I rarely have leading problems, but have learned that the bullet is not holding when the accuracy suddenly goes bad while working up a load.
16. I go through every new or used mould I get, take them completely apart, make sure that they close squarely and completely (with and without the mould handles), make sure they have air vents, and there are no sharp edges or flaws on the parts that move against each other (especially the sprue plate). Use a very fine sharpening stone for any adjustments.
17. I oil the mould after I use it. There is a lot of humidity where I live and there is a rust problem if I don’t oil them. I clean it in soap and water just before casting, then dry it with my wife’s hair dryer. Cleaning them is because trying to “burn off” the oil while casting takes too long. I also preheat the mould in the melt for 60 to 90 seconds before starting to cast (remember to preheat the sprue plate, too). This procedure means that I usually get keepers within 5 casts.
18. I consider the Lyman “Cast Bullet Handbook” to be where to start for beginners (grade school level casting). Col. E.H. Harrison has a book “Cast Bullets” for intermediate casters (high school level). He also put out a very small “Cast Bullets: Supplement No. 1” with additional information. Veral Smith has a book “Jacketed Performance With Cast Bullets” for experienced casters (college level). Beyond that, all you need is practice (experience). Start at the beginning, not at the end. You have to walk before you can run.
19. Just remember that whatever works for you, works. There is no one way to do casting. If you do something different from this and it works, great. If something doesn’t work, consider changing it.
1. I use cast lead, plain-base bullets up to about 20,000-22,000psi chamber pressures (check the reloading manuals for pressures).
2. I use cast lead, gas-check bullets from there up to about 35,000-37,000psi.
3. I use jacketed bullets with pressures from there on up.
4. I have four ingredients that are used for the casting mix. They are:
a. Soft lead at Bhn 5 from salvaged roof sheeting (about 1,100lbs).
b. Wheelweights from large trucks & trailers at Bhn 11 (300lbs).
c. Monotype at Bhn 28 (200lbs).
d. Tin in either pure sticks or (mostly) in 50/50 or 63/37 solder (40-50lbs).
5. I have a bunch of recipes on the wall of my casting room that tell me how much of each material is needed to get a mixture of whatever Bhn I want for the bullet.
6. I air-drop almost all of my bullets onto a towel. Cooling speed affects hardness greatly. The weight of the bullet affects cooling. With bullets using the same melt and air dropped the same, a 100gr bullet will be about 1 Bhn harder than a 200gr bullet, which will be about 1 Bhn harder than a 400gr bullet. Dropping the bullet into cold water is another thing altogether and I have not done much of it.
7. I try to match the chamber pressure to the strength (hardness) of the bullet: ie, Chamber Pressure divided by 1,422 to get the desired Bhn to use for whatever plain-base bullet I am using. That means I stop at about Bhn 15-15.5 for them. I know there is a lot of criticism of this formula around here, but when I use it, I have very few problems. The more I exceed this limit, the more problems I have. In the past, I had to spend a lot of time working out the problems (due to exceeding the limit) and decided it was a waste of time not to use the formula.
8. I use Bhn 15 from then upward for gas-check bullets. That may be a bit lazy. I have seen some indications that I could probably go back down on the Bhn when I first go above 22,000psi with a gascheck and work it up to Bhn 15 by the time I get to 37,000psi. I have not experimented with that, though.
9. I use different temperatures for different moulds and mixtures (the more complicated the mould shape – such as hollow-base – and the more antimony, the more heat that is needed), but I seem to run my mix hotter than a lot of people here indicate they do. That means I cast slower than some people here claim, but it is worth it to me. From my tests, a hotter mixture has less variation in weight than cooler mixtures. I use Boric Acid to cover (protect) the top of the melt rather than fluxing constantly (this is with a bottom pour furnace).
10. I have had more problems with a melt that is too cool than with a melt that is too hot. Frosted bullets shoot just as well as shiny bullets even though they might not look as pretty. The only problem with high heat is when a bullet is partially frosted (especially a long rifle bullet). A partially frosted bullet is not usually straight. The major problem with high heat is when someone strikes off the sprue plate too soon. I am not advocating too high a heat here. Excess heat slows everything down, but otherwise, it is not the kiss-of-death some here have claimed.
11. I get as large a glob of melt as I can on the sprue plate (before it runs off the side). I expect it to stay molten several seconds before it flashes over. During that time, a dimple should form over the sprue plate hole. If there is no dimple, there will be much more variation in weight. I never do anything to speed the flashover (such as putting a fan on it or a damp cloth). I want the melt to dimple and that takes a little time. I am not saying anything against those who do accelerate the sprue cooling, but it doesn’t work for me.
12. Tin is a wetting agent and makes any mould cast better. Antimony is an anti-wetting agent (or clotting agent) and makes any mould harder to cast with. If I have problems when casting with a mould, I add heat progressively until I can cast easily or the pot will not get any hotter. If there are still problems (pretty rare), I will start adding tin until the problem goes away.
13. I normally use a minimum of about 2% of tin in the melt (one oz of tin to 3lbs of soft lead). If I am using antimony, I use a minimum of 2% of tin, but try to keep the amount of tin approximately equal to the amount of antimony. Some people here use 1/2 of the amount of tin than they use of antimony (or less). That can be done, but it is more difficult to cast with (more rejects). Besides, using more antimony than tin makes the bullet more brittle.
14. I start out with bullets sized 0.001” over the slugged bore size. With guns that are properly sized (chamber, throat, and barrel), that usually works fine. It the chamber or throat is larger than the barrel, I usually go to the largest bullet that will chamber easily. The bullet squeezes down in the forcing cone, but is still more accurate than if the bullet is sized for the barrel (but undersized for the chamber/throat). If the chamber or throat is much smaller than the barrel, I usually go to soft bullets sized to fit the chamber with a small amount of fast powder (light loads). This is to “bump up” the bullet and is the hardest combination to get to shoot well.
15. I have tried several types of bullet lube, but have brought them down to three: SPG for anything under about 800-850fps (for both Black Power and Smokeless). Tamarack (NRA 50/50 formula) for just about anything over that speed. If I have problems with the Tamarack lube (usually when pushing the maximum pressures listed above, particularly in rifles), I put a little Lee Liquid Alox over the bullet and the Tamarack. It is double lubed. I rarely have leading problems, but have learned that the bullet is not holding when the accuracy suddenly goes bad while working up a load.
16. I go through every new or used mould I get, take them completely apart, make sure that they close squarely and completely (with and without the mould handles), make sure they have air vents, and there are no sharp edges or flaws on the parts that move against each other (especially the sprue plate). Use a very fine sharpening stone for any adjustments.
17. I oil the mould after I use it. There is a lot of humidity where I live and there is a rust problem if I don’t oil them. I clean it in soap and water just before casting, then dry it with my wife’s hair dryer. Cleaning them is because trying to “burn off” the oil while casting takes too long. I also preheat the mould in the melt for 60 to 90 seconds before starting to cast (remember to preheat the sprue plate, too). This procedure means that I usually get keepers within 5 casts.
18. I consider the Lyman “Cast Bullet Handbook” to be where to start for beginners (grade school level casting). Col. E.H. Harrison has a book “Cast Bullets” for intermediate casters (high school level). He also put out a very small “Cast Bullets: Supplement No. 1” with additional information. Veral Smith has a book “Jacketed Performance With Cast Bullets” for experienced casters (college level). Beyond that, all you need is practice (experience). Start at the beginning, not at the end. You have to walk before you can run.
19. Just remember that whatever works for you, works. There is no one way to do casting. If you do something different from this and it works, great. If something doesn’t work, consider changing it.