The Point Form Die (PF-1) puts the ogive curve on a lead or jacketed bullet. It is used after the core has been seated in the core seating die, which in turn is used after the core has been swaged to proper weight in the core swage die. The PF-1 die is the third die of a 3-die set, the most commonly used set of swaging dies for jacketed bullets.
Point forming dies have the curve of the bullet shaped smoothly into their die cavity walls, and do NOT use a nose forming punch. The internal punch is used to eject the bullet. Except for special custom dies with adjustable internal punches, the internal punch is a fixed length tempered spring wire attached to a punch head, which in turn is retracted by a steel pin (in the S-press) or by a powerful spring (in the CSP-2 or Hydro Press) when the press ram is raised.
The PF INTERNAL PUNCH, or EJECTION PUNCH, consists of a HEAD (which holds the ejection pin) and the EJECTION PIN. The diameter of the ejection pin has to fit a hole in the threaded end of the point forming die. The size of this hole is the minimum size to which the tip of the bullet can be closed in that die. It has to be large enough so that the area of the pin tip spreads the ejection pressure over enough area, in a given bullet diameter and ogive shape, to avoid penetrating into the bullet material, and large enough to allow sufficient strength to prevent bending under ejection force.
Another kind of die with an ejection punch is the END ROUNDING DIE, used in a CTJM-1 Tubing Jacket Maker. The pin diameter is large enough so it will not push through the opening left in the rounded tube base. Over the years, Corbin has determined the minimum practical ejection pin sizes which give satisfactory life, allow for a reasonable degree of operator error, and provide reliable ejection without penetrating the typical jacket material.
Table of pin sizes versus calibers.
Synchronized (sync) ejection pins in point form dies.
Special Notes and Applications:
The above table is generally accurate for the specified kind of die and caliber of bullet. In some cases where the ogive shape requires a larger diameter to minimize deformation of a large lead tip, or if the ejection pressure is higher than usual because of specific non-standard materials or design features, a different ejection pin diameter may be used. Ejection punches used with the ULD-TIP dies typically are made 0.157 diameter to allow sufficient support for the tip inserts, but they are not simple spring wire pins.
SMALLER THAN STANDARD PINS
Sometimes clients insist on smaller diameter ejection pins than we recommend. While sizes that are not recommended can be used, there will be no free replacement or guarantee of operation if the pins bend or stick in the bullet. One size smaller pin MAY work fine for you, with a careful operator and ideal lubrication, and all other factors being just right. The odds are that a smaller than recommended size will not work for the majority of users. If you want to take the risk and will be happy buying replacement pins frequently, if necessary, that is fine. Otherwise, use the standard sizes which work every time, with correct operation and materials.
For example, if we normally use .092 inch ejection pin size in a .308 die, and you want to use a .062 diameter pin, the odds are extremely high that the smaller pin will bend or penetrate the bullet. Maybe not on the first try. If you were to ask for a .082 diameter pin, at least with some care you have a fair chance of it lasting and not sticking much more often than the right size for the caliber.
LARGER THAN STANDARD PINS
On the other hand, if you want a round nose lead tip .308 bullet, you might find that a .120 pin actually does a better job than the standard .092 pin, because it spreads the force over a greater area and doesn't "mark" the soft lead tip as much when ejecting. Any caliber for which you want a 1-E, 3/4-E or 1/2-E ogive shape with a lead tip might benefit from using a larger than standard ejection pin. But the standard size works well, even if it may require a follow up with the lead tip finishing die. Sharp or radiused small tips almost always require the lead tip die as a final step. Putting the cup or cavity in the ejection pin just turns it into a "cookie-cutter" due to the ejection pressure in the point form operation.
CUSTOM LEAD BULLET DIES
For making lead bullets, or in some cases bullet that always have a large flat lead tip, we can make a custom "synchronized" ejection pin that is a pressure sealing punch fitted snugly to the die's ejection pin hole. The depth of cavity and the length of the pin and punch head are adjusted carefully so that the pin tip seals the end of the die cavity. The bullet tip is formed against the pin end, unlike a normal point form die where the pin take no place in actual bullet forming.
This means the pin has to be able to withstand the swaging pressure, and also seal against lead extruding up the ejection pin hole. The normal point form die does not require a honed pressure sealing fit or precise length adjustment, both of which take considerably more die-making time. This is why a custom point form die made to finish the bullet tip without using a lead tip die costs more than a standard point former.
SMALLEST PRACTICAL EJECTION PIN
The smallest ejection wire we use is 0.047 inches, on sub-calibers, if the tip needs to be very small. This size of wire will fold on itself when used in .224 and larger calibers, or penetrate into the tip of the bullet and cause the bullet to stick in the die. Please don't insist on a .047 wire or smaller in calibers that won't allow it to work! We won't do it because it won't work with any reliability. The .047 wire can be requested for .102, .122, .172, .192, and .204 diameter bullets, or for other "sub-calibers" (any caliber less than .224 diameter). If you don't request it, we will use the standard 0.062 ejection pin instead, unless the die set is already made and in stock with the small pin (such as die sets listed on our "specials" page on the web store).
BENEFITS OF STANDARD SIZES
A good reason to stay with standard diameter ejection pins is for replacement parts. If you order an ejection pin for a given caliber, and don't specify the pin diameter, we will send the standard size on the assumption that you have a standard die. If you provide the pin diameter when you order, it can eliminate getting the wrong size of pin and having to send it back. Standard diameter pins, and the dies made to accept them, are more likely to be in stock. Custom or special sizes by their very nature probably have to be built to your order. This may take considerably longer to do than taking one off the shelf. Generally there is no major advantage in changing pin sizes that cannot be achieved better by some other means, such as the tip closing punch in a LT-1 die.
MAKING SMALLER OPEN TIPS
A better way to make a smaller tip is to use a tip-closing die (which is a lead tip die with a hardened punch having a slightly smaller radius ogive than the point form die. This vectors force to the tip of the open jacket and nudges it to a smaller diameter than can be done by the point form die). For the ultimate small tip, in calibers from .284 up, use the ULD-TIP design with the needle-sharp tip insert.
REPLACEMENT PIN SETS
Spare or replacement ejection pins are sold in packages of 5. The length of the pin is made for the length of the die. Most -S type dies use the same length of body and wire regardless of bullet caliber or length. The -M type dies use slightly shorter pins. The -H type dies can be made with different lengths of die body depending on the length of bullet. For them, we need to know the over-all length of the point forming die, or the length of your old ejection pin. If you bent or broke the pin, the die length itself will be sufficient information (along with pin diameter). The pin diameter is marked on top of each point forming die, along with caliber and the letter P and the ogive shape code such as 6-S or 1-E.
SET SCREW RETENTION
Ejection pins normally can be replaced by loosening a set screw in the punch head. The correct diameter of wire is marked on the punch head, and on the top of the die into which it fits. The standard spring wire tolerance may allow for a .001 inch smaller wire than the listed size, such as .061 instead of .062. This makes no practical difference in operation, and pins marked with a .001 inch larger or smaller diameter can be used interchangeably with dies marked either way. A .091 marking on a die is compatible with a .092 pin, for instance. Over time, the supply of ejection pin wire may vary slightly in diameter, and the tolerance range has been allowed for in building the tooling.
A word about the set screw holes in the ejection pin heads: Ejection pins which have one set screw may have the tapped hole passing through the punch head, especially on -S type punches. Even though the hole may be threaded through both sides, only one set screw is generally used. The set screw pushes the wire pin slightly into the opposite hole, putting a very slight bump or flex in the wire. This holds the wire even more firmly than pinching it between the ends of two set screws, especially on smaller diameter wires.
On larger wires, sometimes two set screws are used if the pin will not flex sufficiently into the opposite hole. Threads going all the way through the punch head hole on both sides simply allow for faster production than using a flat end tap. Long tapered taps enter more easily and cut better threads with better chip clearance than blind hole taps. Also, the set screw can be installed more quickly without having to inspect the holes if the threads are all the way through both sides.
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