Just curious if anyone has ever seen this before, or know what it is. Doing some load development on a 26 nosler. These were 147 ELD-Ms RL33 Powder. Know what caused the helical residue on a few of these shots? I have never seen it in thousands of rounds, and no other rounds showed this phenomena. My thought was that the barrel was just completely fouled, but groups fired after this one did not shot the pattern.
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