Firing Pin Bushing and Primer Size

[caveshooter]

My understanding is that bushing the firing pin will reduce the primer from flowing into the bolt face firing pin hole which could potentially led to a pierced primer. I watched the Gre-Tan video, the problem is explained very well and the solution makes sense. In general, is this a potential problem mainly associated with small rifle primed cartridges being used on a large primed cartridge bolt face, say a rifle conversion from 308 to 6BR? This leads into the next question, do production rifles like the M700 or M70 use the same firing pin diameter between small and large primed cartridges?
Just trying to understand the circumstances which cause this particular problem and solution to arise. Thanks.

 

[Alex Wheeler]

The larger the pin the more pressure the primer can put on the firing pin and push it back into the bolt causing a "crator" or if severe enough a blanked primer. Pounds per square inch, more area, more pressure. It has less to do with the fit of the pin to the hole and more to do with the size. Bushing it down cures this for the most part. It has nothing to do with if its a large or small primer. Also the smaller pin transfers more energy per square inch to the primer itself. That may improve ignition, but how much? Negligible I'd say. Crators dont really cause any harm. You may cure them with a new firing pin spring and/or added weight to the pin as well.