Hmmm my first thought would be move to a slightly slower powder to take advantage of the slightly larger case capacity. I don't have my burn rate chart handy and I don't use any of the powders you mention, but my first instinct would be to go up to maybe Varget, h4895, or RL15 and go back to the Nosler 60's since they were working well before and during your fire-forming. I have had great luck with RL15 in the 223 based cases in the past.
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