Concentricity, Bullet Alignment, and Accuracy — Basic Principles

[REELDOC]

I have to admit that I was anal enough as one time to worry about concentricity and runout. After my head started to explode I put the gauge away.

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[Downeast]

Chasing that rabbit down into that proverbial black hole. 🤣

Now Sinclair makes great products but if you were to purchase all of the products listed in that article and actually used them it would take you a very, very long time to load just one round. And then you would be checking that round a dozen times to see if it met all of the parameters.

 

[Howland]

I wanted to see how concentric my ammo was and whether it affected accuracy. I bought a tester, loaded 50 rounds and measured each one, sorting by best to worst.

All showed less than 0.0015" at the ogive which wasn't unexpected as that is about the same variation I measured of neck wall thickness.

The best showed about the same halfway between the ogive and tip. Again, expected. The worst showed 0.0045" at the same location. Now to the range.

The worst shot a slightly smaller group than the best, both under 0.6 MOA.

The concentricity tester now sits on the shelf collecting dust. I still maintain that it was money well spent because now I know instead of wondering. I can always pull it down and use it again if I ever feel I need it.

 

[THE PUNISHER]

I believe neck tension is the biggest accuracy maker/killer. I’ve seen people have pressure gauges hooked up to a press to see how much pressure or neck tension to seat or hold a bullet. During my 1000 yard shooting days I sucked at the whole neck tension thing... that’s why I always shoot new brass to score and brass that had been shot was reloaded to “sight in”.

 

[COTTON]

Went through that many yrs ago. Now I shoot for first round impact, don't worry about little groups. Like punisher said neck tension means a lot. When I seat bullets, those with light tension go in one rack and tight in another.