You have a huge carbon ring just at the beginning of the rifling. With a tight fit jag/wet patch, does the cleaning rod begin to turn with the rifling as soon as you start to push the patch through the bore from the chamber end? If not, you have carbon/copper buildup.
Or..the headspace is not correct.
Or...the firing pin is protruding too far.
Or.....yer just lucky. :)
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