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About Corbin Standard Ejection Pin Sizes

Each caliber of point forming die uses a standard diameter for the ejection pin wire, based on suitable strength to resist bending and to avoid penetration of the lead core, by spreading normal ejection pressure over a wide enough area. The stock or standard dies have these standard ejection pin holes in them. Using a smaller wire size than the standard one may not be reliable and cannot be warrantied to eject without penetration of the bullet or bending the pin. Larger diameter pins than standard are fine, but require building a special die to your custom order.

Ejection pin sizes are industry spring wire diameters, and can vary somewhat from the nominal size. For example, a die marked .061 may use an ejection pin that may actually be .061-.063 inch diameter. The pin need only to fit the hole in the die reasonably well, as it does not need to seal pressure. It only acts to push the bullet out of the die, and takes no place in forming the bullet tip under normal use. Bullets are pushed into the cavity of the PF die only until the jacket end reaches the start of the ejection pin hole. Pushing them further results in material being extruded up the ejection pin hole, and puts a "pipe" on the end of the bullet.

Special (custom) point forming dies with pressure-sealing honed fitted and synchronized length pins can be ordered to allow the ejector to play a part in forming the bullet tip, creating a small hollow cavity, seating an insert in the bullet tip, finishing a lead tip, or performing other functions that are not normally done within a standard priced point form die. The diameter of these special "sync" pins can be virtually any size, although the ULD-TIP dies generally standardize on a specific diameter.
CaliberPin Size
.224 and smaller.062
.243.072
.257 to .284.081
.308 to .318.091
.323 to .375.105
.400 to .458.120
.475 to .512.134
Calibers which are close to the above standard sizes generally use the pin size of the next larger caliber, but since they are not "standard" calibers, and may require making custom tooling, the ejection pin can also be custom without adding to the die cost. This is also true for custom shapes of bullets regardless of caliber: when custom reamers and laps are required, it doesn't affect the cost to also make a custom ejection pin size, whereas a standard caliber and ogive shape for that caliber which is usually kept in stock would become a custom, one-off die if the ejection pin size is specified as a non-standard one for the caliber. This is because it is more cost effective to make groups of the same design at one time for stock than to make a single die, due to the setup and machine retooling time. The smallest ejection pin wire available is 0.047, which may be used only for the smallest of sub-calibers with any chance of reliable operation. It is not recommended but has been used by experienced bullet makers who avoid using techniques that can bend the pin.

To close the open tip further than the diameter of the ejection pin, use a LT-1 lead tip finishing die along with a special "tip closer" internal punch for the caliber and ogive shape. This punch vectors force inward toward the bullet axis, and helps to bring the open tip to a smaller size. Pushing too hard simply puts a ring in the ogive once the smallest practical open tip size is reached for a given jacket wall thicknes, ogive shape and caliber. Using the standard lead tip internal punch generally is not as effective at closing the tip of an open tip jacketed bullet, because the normal lead tip finishing punch cavity is the same as the ogive of the bullet, and has very little or no effective vector for squeezing the tip smaller. The special tip closer punch cavity is made with an ogive having slightly wider angle than that of the ogive for which it was built to make smaller. This creates a small vector angle for the axial force to squeeze the tip inward using light pressure. If a step is formed lower in the ogive curve, it means too much force was used.


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