4064 is great in a 308, never used 4320.
Try to set your collet die to .002 neck tension or so, basically interference fit for your billet and and the neck if the brass. (measure neck diameter of a lloaded round. Then while resizing adjust it so the neck of a sized case is .002 less in diameter) try .001-.004 if .002 doesn't shoot well(it's a good starting point). After 4-5 shots if the rounds become hard to chamber, FL size once, then continue neck sizing
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