One of the keys to accuracy is matching the bullet the bore. A bullet .001"-.002" smaller than the bore is needed to obtain a good fit and still slide the barrel during a match.
I found these pin gauges on Amazon and will be ordering several from .575" to .582".
HHIP 4103-0500 Replacement Pin Gage, P-2 (-0.0002) Tolerance, 0.5": Amazon.com: Industrial & Scientific
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