Thread: 50% fail rate
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Old May 27, 2012, 02:46 PM   #21
Join Date: March 4, 2005
Location: Ohio
Posts: 13,715
As noted, your dud firing pin mark is well off-center. The primer has a anvil inside that is like an upside down tripod. When the firing pin indents the cup, the priming mix is supposed to be squashed between the center of the primer cup and the top center of the tripod to fire it. Your off-center mark looks like it could have missed the tripod tip completely. As mentioned, this is an indicator of incomplete lock-up, where the barrel has not got 100% up into position because the slide is not 100% forward, so something is preventing that. Check the second list of causes I gave.

To get your seating die set up correctly:
  • Back the seater plug's stem out a few turns.
  • Take a loaded dud round and run it up into the die, then then turn the die body down until its crimp shoulder stops on the case neck.
  • Measure the diameter of the case mouth with a caliper. It should be between 0.467" and 0.473" wide.
  • If your case mouth is any bigger: Keep turning the die body down in small amounts until the case neck is inside that number range.
  • Once you have that adjustment done, tighten the lock ring.
  • Next turn the seater plug stem back down again until it stops on the bullet, then tighten its lock nut.
  • Make a fresh round and make sure the bullet seating depth and case mouth diameter are still satisfactory. If not, adjust as needed.
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