Lead wire can come from Corbin in spools (LW-10, 70,000 grains = 10 lbs.) in a diameter that fits into the die (can be smaller by as much as .025 inches without any problem), or it can be your own scrap or ingot lead. Corbin provides 99.95% percent pure lead wire on large-core spools, individually boxed, with a 10% discount in cartons of four spools of the same diameter wire (Order LW-40 followed by the wire diameter. Because of the infinite variety of possible alloy mixtures, Corbin only stocks pure lead wire.) A lead wire extrusion calculator program, DC-LEAD, is available from Corbin on CD-ROM. It calculates volume, length, pressures, and even the size of equipment needed, including adjustment for alloy hardness.

The standard diameters are:

0.125 0.170 0.185 0.218

0.247 0.275 0.312 0.340

0.365 0.390 0.430

Lead wire larger in diameter than 0.430 inches is difficult to coil on reasonable sized spools, hard to straighten and difficult to cut, so very large lead cores are usually cast (in the .50 to .75 diameter range, or above).

Lead wire smaller than .125 is available but it is much more difficult to extrude (pressure is an inverse square function of wire diameter with a given size starting billet of lead) and coiling requires special handling to avoid stretching and breakage. Therefore, the cost is somewhat higher for small diameter wire.

Corbin offers 0.100 special size lead wire for calibers such as the .123 lead and .142 jacketed. This is the LW-10S (in 70,000 grain spools) and LW-40S in cartons of four spools.

The convenience of cutting wire instead of casting tiny cores far outweights slightly higher cost, for most bullet makers. In 0.100 diameter, the LW-10 wire will make nearly 10,000 7-grain .12 caliber pellets or 15-grain jacketed .14 caliber bullets (since the jacket weighs nearly as much as the core).

Corbin's World Directory of Custom Bullet Makers has listings of nearly 200 sources of lead, including most of the world's largest suppliers, who can tell you where to purchase lead wire or ingots from their distributors and "fabricators" (as the makers of lead wire are called). In addition, many custom bullet makers who have the Hydro-Press offer extruded precision lead wire to other bullet makers, and this is noted in the listings in this useful reference book.

1. Melt enough lead to fill one bottle cap with unknown sample, and the other with known pure lead. Make sure the surface is smooth and flat when the lead hardens and cools.
2. When the lead is cold, put the ball bearing between the two lead surfaces and squeeze this "sandwich" in the vise until the ball is driven partly into both surfaces (just enough to make a fair sized dent, but not past the middle of the ball).
3. Remove the sandwich and measure the two dent diameters. First measure the known pure lead dent and write down this number. Then measure the dent diameter in the unknown lead sample and write it down. Square both numbers (multiply times themselves). Then divide the resulting square of the unknown lead dent diameter into the square of the known pure lead dent diameter. This could be written as (L times L) divided by (X times X) where L is the pure Lead dent diameter, and X is the unknown lead dent diameter.
4. The answer should be a number of 1 or greater. If it is a fraction, or less than 1 in value, you have inverted the two dents and divided the wrong way. In that case, try again. When you get an answer that is 1 or greater, multiply it by 5. This is the actual Brinnell Hardness Number of the unknown sample.

The new design of core mold is built with a solid block of cast iron having four bored holes fitted with pistons, very much like a straight line car engine. A long steel sprue plate pivots over the top of the mold, similar in some ways to the head on an engine block. The sprue plate is moved to one side to cut off the four small connecting links between an open "bathtub" at the top of the sprue plate, and the lead in the cylinders. When the sprue plate is moved to the side on its pivot, a rest plate or bar at the bottom of the mold can be pushed up to eject all four of the lead cores at once.

The sprue plate is then swung back into position, so that the four small holes connecting the depression machined into the top will align again with the four cylinder holes. A pick or needle nosed pliers can be used to put the remaining sprue (left over lead in the open top of the sprue plate) back into the lead pot.

The improved core mold can be adjusted for length of core, so you can set the core weight. This is done by adjusting the position of the nuts which support the rest plate, which both ejects and supports the four pistons. Lowering the rest plate position also lowers the pistons, so the cylinders hold more lead. Raising the rest plate reduces the core weight. A considerable range of weight can be made with the core mold. The precision of weight control is reasonably good, so that one can use the cores without pre-swaging them if desired. Usually with the reloading press swage die sets, where the goal is to make bullets in the lowest cost manner without investing in a swage press, the core mold is used without a core swage step. Weight control of around 1 to 2% of total bullet weight is achieved.

For more precise weight control, a core swage die is used to slightly reduce the cast core weight while making it more uniform. Weight tolerances of less than 0.5% of total bullet weight can be achieved with the core swage step. Whether this is needed or not depends on the shooter's purpose. For hunting purposes, a 1-2% variation in bullet weight makes no difference. For benchrest shooting, every possible benefit is desired including the tightest possible weight control (although below 0.5% of total bullet weight, the effect on bullet group is virtually non-existent).

References in earlier literature or prior website images of the CM-4 and larger CM-3 core molds are still valid for the new CM-4a, except that the possibility of much larger core diameters is combined with the ability to get four cores per cast. Previously, a larger core required one less cavity to avoid excessive heat radiation (too rapid cooling between casts). The mono-bloc style mold allows both a larger bore and more bores closer together and retains heat between casts. The core molds are not made with a combination of sizes in one block, nor can the molds be changed from one size to another, since there is no sleeve or separate cylinder wall as with the earlier design. However, this also means there is no cylinder tube to become loose from repeated heating and cooling, making the CM-4a a more reliable product as well as extending its range of sizes while reducing the cost over that of the earlier CM-3 for larger cores.

You can also extrude your own lead wire, making a profitable secondary product to sell. The lead wire extruder fits the larger Corbin Swage Presses, either the Hydro-Press or the Hydro Junior. It is not practical to extrude lead wire in a hand press of any size, except for the tiny .14, .17 and 5mm calibers. You only get a few inches of lead on each stroke of the press, whereas with the power machines, you can get yards of lead on a single stroke.

PAPER PATCHED SLUGS

A paper patched slug can be swaged in three ways. First, you can make a slug with a small fouling-scraper shoulder. This is like a cylinder with a slightly smaller diameter nose attached. The nose can be any shape (round, conical, spitzer, Keith, wadcutter, etc.) so long as it attaches to the body of the bullet (the parallel section) with a small (.015-.020 inch) shoulder. A single stroke in a single die, typically the LSWC-1- type, both adjusts the weight and forms the nose and base. The base can be flat, cupped, hollow, dished, rebated boattail, or any other desired shape. Both the nose and base are formed against the ends of punches, which can be changed quickly and cheaply for different shapes on either end. The weight is adjustable over a wide range. Only the diameter remains fixed for a given die.

In a reloading press, the weight is adjusted by using a special "bleed" type punch (external, fits the press ram like a shell holder). Then the punch is changed, and the nose (or base) punch is inserted and used to finish the bullet. In a Corbin press, the die itself has bleed holes to adjust the weight all in one stroke, without changing punches.

A more nearly perfect bullet can be made in two operations, using a separate "core swage" die and a second "core seating" die. By separating the weight adjustment step from the nose and base forming step, long hollow cavities and sharper noses can be formed more precisely than if the pressure is being released through the bleed holes at the same time as the lead is trying to fill out the complex, small shape of the nose or cavity. In very small bullets (pellets) or with thin skirted hollow base bullets, this is highly recommended over a single die operation, but both usually work. The two die operation is available in Corbin presses and dies made to fit them.

From left to right: 1-E, 3/4-E and 1/2-E nose shapes. The typical paper patch rifle bullet made in a single die uses the 1-E ogive.

These bullets can also be made in a style that has a tangent ogive (no shoulder). This requires at least two dies. The first die is a core swage or a LSWC-1 style (for this application a CSW-1 core swage and a LSWC-1 lead semi-wadcutter die are used the same way). The second die is a point forming die, which has the curve of the bullet nose formed in the die rather than a punch. This is slightly more expensive than using the two straight-through dies, because a point forming die is harder to make. But it eliminates a slight drag effect on the shoulder and thus the bullets have higher BC for long range or high velocity shooting.

A paper patched bullet is always made smaller than the groove-to-groove diameter of the barrel. For example, if a normal jacketed bullet would be .458 diameter for the .45-70 barrel, then a paper patch bullet for the same gun might be made .448 to use with 1.5-inch thick paper wrapped around twice. Or it might be made .451 or .452 diameter to be used with thinner paper. The diameter you want depends on both the groove depth and the bore size, and the paper thickness. A common formula is to use groove to groove diameter minus four times the paper thickness.

Bullet bases, left to right: Base Guard, Cup Base, Dish Base, Flat Base. The Cup Base is typically used for paper patched rifle bullets.

A variation on the paper patch bullet is the TEFLON TAPED bullet: instead of using paper after swaging, a wide 3/4 inch teflon pipe tape is used around the bullet. If you first swage the bullet almost to size, perhaps .005 inches smaller, and then wrap it and swage again in a slightly larger die (final size), the lead will gently push out against the tape. It could otherwise be pulled off if you tried to put the bullet back into the same size die that built it without the tape wrap. This method uses two dies, but you can make one of them the final size for a lead bullet without a patch and the other .008 inches smaller so it can be used with regular paper patching also. This gives you three different bullets with two dies (base guard or knurled lead in the big die, paper patch in the small die, and teflon patch using both dies in succession). For more info, go to Paper Patch page.

BASE GUARD BULLETS

A Base Guard is a trade-marked name for Corbin's fouling-scraper disks attached to the bottom of the bullet at the same moment the bullet is formed. These disks form a sharp burnishing tool edge, which scrapes fouling out of the bore with every shot. The disk rotates with the rifling, regardless of whether the body of the bullet skids or fails to turn in the rifling, and thus seals the bore against powder gas (unlike a gas check, which is crimped on the surface of the bullet and cannot turn separately from it while in the bore).

Base Guard disks eliminate the need for lubricant or paper patching. They cannot be used with a hollow, boattail, rebated boattail, or any other base style except the standard flat base having a BG dimple to allow lead to flow through a hole in the disk, and attach by forming a rivet head on the opposite side. Their advantage is extreme speed of manufacture, high degree of accuracy, automatic cleaning of powder and lead fouling from the bore, and elimination of traditional lubrication. However, they do not work in all bores because if the bore has exceptional roughness, a swelling or uneven diameter, the gas will escape around the disk and cause gas cutting of the bullet, and the bullet lead will seep past the disk at any point where there is not a perfect seal between disk and bore.

About one in ten barrels seems to have a problem with leading (of course, this means 9 out of 10 work fine). Base Guard disks are applied in either the LSWC-1- type of die, or in the two-die operation where a PF-1 is used. If the two-die operation is used to eliminate a shoulder, then both dies must use a punch on the base end that supports the rivet head shape holding the disk to the bullet (smashing the rivet head with a flat punch can allow it to pull off the base in flight, resulting in two holes in the target in most cases because the airflow dynamics hold the disk to the base until just before it strikes, and it usually does not have time to turn before hitting the paper.

CORBIN DIP LUBE

Liquid jacket is one of the terms used to describe Corbin's Dip Lube, a synthetic polarized wax in an organic solvent carrier (naphtha). The wax molecules attach to metal with very high electrostatic adhesion. This thin, almost invisible coating of wax withstands high speed and temperature. A small amount of wax can be used to hold other lubricant materials, such as fine graphite and/or moly disulphide powder. A swaged lead bullet can be dipped with a strainer into a can of the lube, or a quantity of bullets can be set up in a pan and the lubricant poured over them. A few ounces of lubricant will last for several hundred bullets. Some commercial bullet makers use a spray to apply the lube as the bullets pass by on a track or rotary table of their own design, and then dust the damp bullets with a cloud of powder lube, resulting in a very even coating.

KNURLED BULLETS

Knurled bullets hold far more lubricant in contact with the bore than a grooved, conventionally lubricated bullet (such as most cast bullets). The surface is covered with a fine diamond pattern, like reversed checkering, that holds a conventional or a dip-type lube against the bore, like a waffle holds syrup. It's easy to apply knurling to any finished lead bullet with Corbin's HCT-2 Knurling tool. Just put the bullet on the two rollers that make up the V-way, close the handle and turn the crankshaft one or two revolutions. Then dip the knurled bullet in Corbin Dip Lube, or pour a conventional Alox-type lube around a pan of them and use a closely fitted tube or case to cut them out of the lube. Other methods include dusting with graphite and/or moly disulphide powder and then re-swaging to trap the lubricant in the knurling under high pressure. Re-swaging brings the size of the bullet back to precisely the right diameter (knurling increases the effective diameter slightly).

GROOVING TOOL

Any lead bullet can be grooved with Corbins HCT-3 grooving tool. The grooving tool places two serrated grooves on the bullet, at the same time. You can move it and place two more if you wish. The most precise method of lubricating and forming these bullets is to use two different size dies. First, the bullet is formed as a parallel sided cylinder that is .005 to .010 inches smaller than final size. The cylinder is knurled or grooved, and then lubricated by dipping, pouring, or tumbling with appropriate liquid, wax, or powder lubricants (all have been used with success). The grooving process expands the diameter slightly, and the method of lubrication application can add dimensional changes of its own. Then the lubricated, grooved cylinder is put into the final die and expanded slightly to the correct diameter under tons of pressure. The nose and base are usually formed at this time.

By using a two-diameter process and applying lube in the middle of the operation, the bullet comes out with lubricant applied under extreme pressure, making it far more even and free of voids and air pockets than the typical low pressure lubing operation. The final roundness and diameter are nearly perfect with this operation, as compared to cast bullets. Precision is greatly enhanced.

SPRAY-ON DRY LUBE

Corbin offers a spray-on, quick-dry moly lube for lead bullets. The pressurized spray can will coat hundreds of bullets with a light brown colored dry film that protects the bore from leading. Corbin's Moly Spray is formulated to apply a clean, hard coating on the bullet that increases the slickness (reduces friction) of the bullet passing through the bore. The dry film is thin enough so that it does not prevent the bullet from fitting the chamber or cartridge. It must be used in a well ventilated area because of the flammable propellant in the spray can. No open flame, smoking, or sparking machinery should be present when applying the lube (same precautions as you would use with spray paint).

The lube does not soften black powder fouling. If you are shooting black powder, you can use a combination of "hard" wad and "grease" wad, both of which can be made for your gun, either for cartridge or muzzle loading, using a Corbin DCD-1-S or DCD-1-H Disk Cutter Die. The die is similar to the BGK-1-S or BGK-1-H Base Guard die, with a slot through which you pass material as you move the press ram in short up and down strokes to punch out disks. Two kinds of material are punched with the tool. Felt upholstry padding, in a half-inch thickness or less, is turned into felt wads. Stiff "nitro" cards or "hard" wads are made from bristol board or other stiff cardboard.

After punching out a number of each kind of wad, the felt wads are placed in a pan with hot Alox-Beeswax lube mixture (or use your favorite grease normally applied to the bullets). The wads are slowly stirred with the melted lube until they are saturated. Then they are removed, drained briefly to remove surplus grease, and allowed to cool. The hard wad or "nitro card" is placed in the barrel or cartridge first, on top of the powder. The fit is snug, to prevent lube from contaminating the powder. To make sure that the grease won't migrate through some grades of cardboard, test it first for "soak through" by placing some of the lube on one side and periodically checking for seepage. If necessary, spray one side of the cardboard with a grease-proof shellac or enamel paint and allow it to dry before punching more wads.

The grease wad is placed on top of the hard wad, so that when the gun is fired, the hard card acts like a piston and compresses the felt, squeezing lube against the bore. The lube should be a type that softens the black powder fouling, to be effective. The bullet may not require any lubrication, with this system.

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