Hi,
I have a quantity of 7.35 berdan primed cases that I was interested in reloading for. The berdan primers in the cases measured .204 inches. The new boxer primers (no. 200 CCI) measure .2105 inches. This is what I did.
I held the case one at a time in a machinist vise and using a drill press drilled a .070 diameter hole (#50) through the old primer using the firing pin indentation as a guide. This effectively removes most of the anvil. Take your time and be carefull to drill the holes accurately.
Then one at a time using a .187 diameter drill, gently and using an even pressure drilll into the old primer using the .070 hole as a guide just past the cutting angle on the tip and lift the handle on the quill and nine out of ten times the old primer will be attached to the drill bit. Remove it and move on to the next one being carefull not to drill too deep. When all are done move on to the next step.
Enlarge the primer pocket using a .209 diameter drill (#4) just deep enough to go past the cutting angle on the drill tip. Do each one, one at a time until complete. This step will serve as a guide for the next step.
Using a .209 diameter carbide endmill, mill each case to a depth of .125 or just deep enough to remove any of the anvil not removed from the first step, again being carefull not to go too deep. A .209 diameter drill bit with the tip ground flat can be substituted for the endmill but better results will be had with the endmill.
For the last step use a chamfering bit or a larger drill bit to just provide a small lead in for the new primer.
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