Piercd primers from 1920's

@414gates @414gates 10 months ago

Interesting snippet from Hatcher's Notebook.

I've often come across posts on various forums where people enquire about their pierced primers, and seem sure that their loads are not over pressure. My opinion was always that the load is over pressure, the reloader just doesn't know it is.

This explains why primers pierce on normal loads. Especially in today's competition rifles where the weight of the firing pin assembly is reduced, or the firing pin travel shortened.

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@D @ds-j

Would some lease explain this - it does not make sense that something with less weight should cause more damage? Would that be due to the higher speed of the firing pin?

@T @tripodmvr

The stiffer spring and heavier weight stops the indentation in the primer from popping out to the rear.

@414gates @414gates OP

.. it does not make sense that something with less weight should cause more damage? Would that be due to the higher speed of the firing pin?

in this explanation, there is no damage from the firing pin itself

The stiffer spring and heavier weight stops the indentation in the primer from popping out to the rear.

and when it does pop back, it probably weakens that spot further by reducing elasticty from work hardening

An interesting concept, that the firing pin inertia can be overcome by the chamber pressure, causing a pierced primer.

This also might explain why less than max loads sometimes result in a small raised rim around the firing pin impact point.