Light primer strikes are or can be caused by a few things, but 9 times out of ten something is padding the pin fall. A firing pin spring does not instantly accelerate the pin to some velocity, it ramps up. Anything that interferes with it will reduce primer impact energy, that old pesky Energy-weight-velocity thing.Originally Posted by jim36
Excessive protrusion can also cause problems. Since you'll never indent a pirmer more than about .020" a longer static ( bench setup) protrusion can lower impact pressures, the pin is stopped short during it ramp up, it in effect shortens the pin fall length. Its why some of us recommend a shorter protrusion in the .030"-.040 range, +/- .020" for the indent depth and .010"-.020" for the brass head clearance ( bump), primer seating depth and etc.
Padding the fall can be caused by the bolt internals, the sear not being cleanly released, its contacting the stock, the trigger over travel too tight and etc. The sear contacting the stock is somewhat common. A simple test, fire a few primed cases ( no powder-bullet!) with the action out of the stock. If they ignite reliably the sear is making contact in the stock somewhere. If they fail to ignite check the sear operation, trigger adjustment and the bolt internals to be sure the firing pin isn't binding. Since you've tried two bolts I'd discount a bolt problem to some degree.
Where to start? I'd try some primed brass with the action out of the stock then go from there.
Bill
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