Measuring TIR bullet run-out
I'm doing some loading in preperation for hunting season. In checking the runout of the loaded rounds, where should the indicators' tip be placed on the bullet? I'm using a Sinclair Concentricity gauge, and I have the contact points for the case set at just in front of the base, and just behind where the shoulder meets the case body.
I'm finding that I can group the loaded rounds in 3 distinct groups, 1) TIR of <.0015 TIR, 2) .002-.003 TIR and 3) .005-.007 TIR, and they are 60%, 30% and 10% of the loaded rounds respectively. Same brass lot, same bullet lot and all fired in the same gun, same number of firings on the cases.