If all you want to do is get the right equipment for a given bullet, send Dave Corbin an e-mail, fax, or letter describing the bullet you want to make. Give a general range of weights, the diameter of the bullet, and a description of any special features you want. You don't have to read or understand any of the information presented here, in order to get the right package. The equipment comes with complete instructions and samples. But if you WANT to know more, read on...
Jacketed bullets that have a lead nose, with the jacket stopping at a shoulder prior to the nose section, are called "semi-wadcutter" style bullets. The actual shape of the nose can be anything that can be formed in a cavity in the end of a punch. Round, Keith, even full wadcutter styles can all be made with a jacket covering the entire shank or bearing portion in the 2-die set called a "Jacketed Semi-wadcutter 2-die set" or JSWC-2. The -S or -H following it identifies which size of press it fits.
Both the -S and the -H types of dies work the same way. The -H dies are larger and use a 1 inch x 12 thread. The -S dies use a 5/8-24 thread and have a body of from 3/4-inch to 1.0 inch depending on the caliber (small calibers such as .17, .14, .12 and .10 generaly are made with 3/4 inch bodies).
The operation starts with the jacket. The jacket determines the diameter for the core (the filling for the bullet) since solid materials must be small enough to fit inside the jacket before swaging. Very thin jackets, such as those made from fired .22 cases, may only have 0.012 inch thick walls. Thick jackets made from copper tubing may have .035 inch thick walls. Typical commercially made jackets that you can buy in bags of 250 or 500 from Corbin may have walls of .020 to .026 inch thickness (some handgun jackets have thinner walls for faster expansion at low velocities). Most bullets made in the JSWC-2 die sets are for handguns, but they do not have to be! Any caliber can be made in this style.
The jacket determines the size of the lead core (which must fit inside it). Once the core size is known, then a core swage die (CSW-1) can be made to accept the nearest smaller standard size of wire core. Corbin offers lead wire in standard diameters, core moulds so you can melt scrap lead and cast it into variable weight slugs or cylinders of standard diameters, and lead wire extruders so you can make your own lead wire in any standard or custom size.
Generally, you will want a lead wire sized at least .002 inches smaller than the desired core. The wire can be quite a bit smaller, in fact. The only limit is the length of material needed to make the desired weight. If the core is too small in diameter, it will fold or fail to fit into the die before it is compressed and expanded to the right diameter. The core has to fit completely into the die before any pressure is applied, or it will simply buckle and drive the punch to one side, possibly causing damage when the punch strikes the die face instead of going into the die cavity. Also, the swaged core must fit to the bottom of the jacket, or it may trap air. This is especially problematic in bonding cores, because the heat from bonding may expand trapped air and blow the core out with some force.
For a typical .38 or 9mm bullet, with a jacket, you would use .312 diameter lead wire or core mold. This fits inside the jacket. But first, it fits inside the core swage die so you can expand the lead upward in size, shorter in length, and in the process, extrude a little surplus lead and leave the exact desired weight. The core swage might be .318 diameter, for instance, to make the core fit better in a given jacket. We work that out when we make the die set, knowing what jacket you plan to use.
Most .40 or .41 caliber bullets use jackets that will take a .340 diameter lead wire (which fits the core swage, which in turn makes the core a little larger to more exactly fit the jacket). Most .44 (.429) and .45 caliber (.452) pistol bullets can be made with a .365 diameter lead wire. The .45 with a thin wall could also use a .390 wire. Again, you don't have to worry about that because when you order a set of dies for a certain caliber and specify the jacket, we'll make sure the core swage and wire size work with it.
The lead core is cast (using the CM-3 or CM-4 core mould) or cut from a roll of wire (using the PCS-1 or PCS-2 core cutter) to a weight just slightly more than desired. To find out the desired weight, weigh the bullet jacket you plan to use. Then subtract the jacket weight from your desired final bullet weight. The difference is the final core weight. Add a few grains, five or so, to this figure, and make your cut or cast cores about that weight. This insures that your rough cores will have enough extra weight so that they can all be slightly reduced in volume to make them all come out exactly the same. If you cut or cast them too close to final weight, the tolerances in cutting or casting might make some of them too light. Then the core swage could not do anything about weight control, as it can only remove lead, not add it.
Lubricate the lead cores lightly using Corbin Swage Lube. You can roll them on a stamp pad that has been saturated with swage lube, or just put a little lube on your finger and thumb tips, and give the cores a twist as you pick them up. It takes very little lube to put an insulating layer between the die and the material being swaged. The thin but tough film of lube prevents leading and reduces wear. Most wear comes from airborne dust that settles on the material you use (jackets or lead). Silica dust is very hard and abrasive. It comes primarily from gravel roads, drifts for hundreds of yards and gets tracked or sucked into the home or workshop through ordinary foot traffic and ventilation systems. If you suspect that there is a high level of silica dust in the air, you can extend your die life by wiping down the lead wire before you use it, and by keeping your bullet jackets and lead supplies in closed containers.
The core swage die (CSW-1-S) has an "S" marked upon it to indicate "core swage". It also has the diameter of core that it produces. Since one core swage can be used for various calibers of bullets, it does not usually have a caliber indicated. The external punch fits into the top of the press. It could be considered the "top punch", but we call it "external" because it stays outside the die all the time, except when swaging takes place. The internal punch is always inside the die. It seals the bottom or threaded end of the die, and is driven upward to eject the finished core when you lower the press ram. The internal and external punches are marked with "S" and the diameter of core, also. They are a snug fit into the die cavity.
For details on setting up and using a core swage, see CSW.HTM, the core swage page.
In brief, you put the core into the die, raise the ram all the way (make sure the press is in the swaging mode, rather than the longer stroke reloading mode). Adjust the punch holder, in the press head, so that the external punch does not contact the core yet. The punch holder has a bushing that unscrews from the lower end, and fits over the punch. If the punch is larger than .375 diameter (for large calibers), then it will have a built-in hex bushing in the type -S system. The larger -H system does not require a captive bushing until the caliber becomes much larger, in the 12-bore or 70 caliber range. Smaller calibers use the bushing that comes with the punch holder, which in turn comes with the press.
Once the ram has been raised to the top of the stroke, lower the punch holder until the punch contacts the core, and you cannot turn it any further down by hand. Then lower the ram and turn the punch holder slightly lower, a quarter turn or so. Raise the ram. Repeat this process until you get a small amount of lead extrusion or encounter resistance. Lower the ram, eject the core, and weigh it. If it is completely filled out and weighs the right amount, you have the correct adjustment. If it is not yet filled out into a nearly perfect cylinder, or is too heavy, continue adjusting and testing until you get the desired weight. Extrusions will come out of the bleed holes. You can use a catcher tray or wipe them into a container so they don't accumulate. Save them to make fragmenting bullets!
Wash the cores in a solvent to remove lube, or boil in hot water and detergent, rinse, and allow them to dry. Put the dry cores into bullet jackets by hand. Then lubricate the jackets with Corbin Swage Lube. Do not get lube inside the jackets. Anything inside the jacket other than the core will tend to cause imbalances during flight. A clean, dry core is the next best thing to a bonded core. With SWC style bullets, the lead core projects beyond the jacket far enough to form the nose. You may want to experiment with two or three cores of different length to get just the perfect amount of lead beyond the jacket, once the bullet is finished...in other words, don't make 1000 cores all the same weight and then find out they are 1/10 inch too long to look good in the jackets you have! Try one or two first and then make adjustments as needed before going forth with a major project!
Seating the core means compressing the core into a jacket, so that the jacket is expanded to proper size by the pressure on the core. This is necessary so that the jacket will tend to spring back to form a tight grip on the core, and to preset the diameter for best accuracy. The core seating die and punches are marked with "C". Don't confuse core swaging, which is the forming of the filler and adjustment of its weight, with core seating. The core is "seated" firmly in the jacket, using an external punch that fits the ID of the die, rather than the ID of the jacket (which is the case with open tip or full jacket bullets).
A SWC type bullet always uses a lead core long enough so that the cavity in the external punch, which forms the nose in the core seating step, will be filled with lead. If your core is too short (too light for the jacket length) then the edge of the punch will come down against the edge of the jacket. The jacket will be crushed and buckled. Having enough lead to fill the entire cavity of the punch means that the punch can stop short of touching the jacket (or at most, just barely touching it at the edge). Having too much lead core for the jacket length means that there will be lead in contact with the bore.
Lead in contact with the bore is exactly what happens with the so-called "half-jacketed" bullet. This is an early kind of jacketed SWC bullet, not much used today. It simply means that the jacket is shorter than the core by more than the nose length. Some of the core then forms a full-diameter part of the bullet shank. Whether this is "bad" or not depends on the velocity of the bullet. If it is shot very fast it may cause leading, even with half the length of the shank covered by jacket. It can be fired faster, usually, than a gas checked bullet, but not so fast as a 3/4-jacketed SWC. By 3/4-jacketed, all we mean is that the entire shank is covered and only the nose sticks out, beyond the step or shoulder.
Why can't the nose be formed without any step? It can, if you use a third die, which has a curved cavity in the die itself. But with the two-die set, the both dies are straight walled. A full diameter punch forms both nose and base. If we try to make the edge of the nose punch too thin, it just cracks and breaks off under the extreme pressure, when it is pulled back to eject. About 0.015 inches is the minimum edge thickness for the punch, which gives it a good useful life in a properly fitted die (and no life at all if the die is larger than the punch by even a few ten thousandths, which is why you must use the punch that comes with the die, and make sure you don't put a new, properly sized punch into an old, worn-oversized die. The die walls support the punch walls, you see. The punch edge couldn't hold 20,000 psi of pressure by itself, without the closely fitted support of the die itself.
If you try to make too long a bullet for the die and punch combo, the punch may still be partly unsupported, outside the die mouth, when the jacket and core begin to expand and achieve pressure. That can lead to rapid failure of the punch, even if the edge is within the die by some small amount. The entire cavity within the punch should be into the die before any significant pressure is generated. All that means is that you should make sure that you tell the die-makers, when you order, the maximum weight you will ever make in that die if you plan to exceed normal bullet weights for that caliber. Then they can either make the internal punch head shorter, to squeeze as much volume as possible out of the die, or suggest that you move up to a bigger die and press such as the -H system rather than the -S type dies.
Core seating is done with a light touch. Adjust the punch holder as before, using the top of the stroke, but use only very light pressure to seat the core. Once the jacket has expanded to the diameter of the die cavity, you have finished. The jacket and core should stay in the die. This indicates that it has expanded to press against the die ID. If the core comes out and the jacket stays in the die, see if you are perhaps getting lubricant inside the jacket or on the core. Make sure your core is long enough so the nose punch isn't hitting the end of the jacket.
At this point, you have seated the core. The jacket has expanded to completed bullet size. You are finished!
Here are some of the things you might also do in the seating operation:
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