My Knight bare primer Disc Extremes had a different problem. After 8 to 10 shots using the CCI 209M or Federal 209A primer the primers were very hard to extract from the primer carrier due to buildup of blowback residue. Rather than using a shim to reduce headspace in the primer pocket in the breech plug, after learning about the slightly extra length of the regular Winchester 209 primer I tried them the last week of our deer season. Problem solved. Clean primers and no blowby.
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