Measuring bullet runout *Again*

[mtang45]

I know there has been a lot posted on this subject and I think I have read it all. I understand in a V block setup you want to measure just below the bearing surface on the ogive. The part that is unclear, is what part of the cartridge sits on the front V block? Is it the case body, the case neck or the bearing surface of the bullet?

Measuring from the above three positions gives wildly different results. So from where does everyone rotate their cartridges?

 

[BoydAllen]

Gauges support loaded rounds in a couple of different ways. Both ways usually support the back of the case a little ways in front of the extractor groove. The other support is generally just behind the bullets meplat, but not on a SP's lead, or just behind the radius of the shoulder. For loaded rounds, I set up the indicator to make contact about where the shank of the bullet meets the ogive. I don't like V blocks because they have more drag on cases than something like Sinclairs bearing balls, and if the entire body of the case is on one continuous V block, short cases will tend to rock as they are rotated. My H&H has a plastic V block for the back of the case, that I purposely tilt so that it only touches the case on its (the blocks) back edge.

 

[mtang45]

Gauges support loaded rounds in a couple of different ways. Both ways usually support the back of the case a little ways in front of the extractor groove. The other support is generally just behind the bullets meplat, but not on a SP's lead, or just behind the radius of the shoulder. For loaded rounds, I set up the indicator to make contact about where the shank of the bullet meets the ogive. I don't like V blocks because they have more drag on cases than something like Sinclairs bearing balls, and if the entire body of the case is on one continuous V block, short cases will tend to rock as they are rotated. My H&H has a plastic V block for the back of the case, that I purposely tilt so that it only touches the case on its (the blocks) back edge.

Thanks for the reply. My gage actually does have the rollers rather than just a V cut out, so it rolls smoothly. So you are saying the rear support just ahead of the extractor groove and the front support just behind shoulder, on the body and the dial indicator on the ogive just slightly ahead of shank or bearing surface?

 

[BoydAllen]

Yes

 

[mtang45]

OK, thanks again!