Berdan Primer Removal
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Berdan Primer Removal |
Decapping (uncapping)
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Removing spent Boxer primers is usually accomplished using a small diameter pin that goes through the central flash hole, this contacts the underside of the anvil in the spent primer and pushes the primer and anvil out of the pocket. At first sight this seems a simple and obvious way of doing the job, but there are two major snags in this system...
The flash hole needs to be large to accommodate a pin that is strong enough not to bend or distort.
The underside of the anvil is uneven and can result in the contact of the pin causing side thrust and a tipping action that can wear and distort the primer pocket.
The method is very widely adopted and most die sets that are sold for reloading will incorporate such a pin in either a sizing die or a case mouth expanding die. This means that there is no extra time involved in removing the old primers as it takes place at the same time as another operation.
Cutaway drawing of an RCBS .30-06 sizing and primer removal die with the case itself cut away to show the action of the decapping pin. This set up is typical of the majority of die sets. Also shown is a second cutaway that reveals the neck expander plug (button), that works on the inside of the neck as the case is withdrawn from the die.
Some manufacturers offer a "Universal Decapping Die" that will do the job on very many different calibres. Whilst this may seem a useful item... I would recommend that decapping during the sizing operation will give the pin a greater centring effect and thus the least possible damage to the already large flash hole.
The pin in a few types of die is held in a central punch and is free floating in a loose fitting collet. This is intended to allow good self centring of the pin with least damage to the flash hole. In cases like this I recommend that the loose pin be restrained slightly with a paper or plastic collar to restrict the possible wobble on the pin without making it completely rigid. A few turns of nylon sewing cotton or PTFE plumbing tape will often do a good job here.
Hornady 'New Dimension' de-capper die stem showing collet which can be set up to give a very rigid and perfectly central decapping pin.
It is also possible to use the same hydraulic methods, that are used in Berdan primer removal, to extract Boxer primers... With a resultant lowering of primer pocket damage, but nothing can make up for the gross sizing of the flash hole.
Originated... 04 June 2002, Written... 19 to 24 September 2002, New Domain... 19 November 2003, Upgraded... 24 January 2007,
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