Measuring TIR bullet run-out

[esshup]

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.

 

[Capt Kurt]

To get the best measurement the indicator should be placed just back from the tip of the bullet, say 3/16" . If it is a ballistic tip come back on the copper. However each casing neck should be checked before seating the bullet. Necks should have no more than .001 runout. If they do try running them thru the sizing die one more time. If you cannot correct this condition, seating a bullet and correcting bullet runout can only be corrected to the runout measurement of the case neck. Your best ammo will be those that have less than .001 runout in the bullet and case neck combined. Hope this helps. Capt. Kurt