Rimfire bullet concentricity and its affect on accuracy

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Tony Nielson
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Rimfire bullet concentricity and its affect on accuracy

Post by Tony Nielson »

We have posted a technical paper concerning this topic on our website and it should be of particular interest to this group. Click on the title "22-Rimfire Concentricity Gauge" to be taken to the article. Please feel free to email me with any questions.

http://www.nielsonbrothersarms.com

Tony Nielson
Nielson Brothers Arms, Inc.
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Richard H
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Location: Guelph, Ontario
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Post by Richard H »

I'm a quality engineer and spend a good deal of my life measuring things and desiging gauges. Nice design and good idea but $365 with a off brand indciator (use Federal, Mahr or Mitutoyo). How do you claim accuracy to .0005 when you are using a .001 indicator. What is the GR&R for that guage? If you're going to measure this stuff I suggest going to a tenth indicator. Another problem is a stack up of error, you are locating on the outside case and rim, any runout error will show on the indicator and it has nothing to do with concentricity. (you're actually checking runout to the rim and case not nessarily the center axis).
Tony Nielson
Posts: 14
Joined: Sun Aug 01, 2004 11:55 pm
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Post by Tony Nielson »

Richard,

I hope I can address your concerns with the following. First the price. This is a well machined unit which takes approximately 6 to 8 hours of machining time to create. At $365 per unit that is roughly only $40 per hour. Obviously a very good value considering that from there we have to pay all of the costs associted with running the business and liabilty insurance and hopefully have some profit left over for us. Profit is not evil.
Second would be your assumption concerning how the measurement is taken. We are spinning the axis of the case on its centerline and measurinig the axial relationship of the bullet to this. Minor varriations in the case in the 0.0000 range become insignificant to this measurement. The whole point of this bullet concentricity theroy is that if we sort the ammo to the 0.000 range we see improved accuracy. It is not necessary to go to the extremes that you are referring to. The 0.0005 guarantee is for how accuratley the shafts will spin the case itself.
Please let me know if I can answer any additional questions for you.

Tony Nielson
Nielson Brothers Arms, Inc.
tnielson@vcn.com
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