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Old 11-08-2006, 11:39 PM
R.G. Robinett R.G. Robinett is offline
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Join Date: Sep 2006
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Quote:
Originally Posted by jim saubier View Post
We make .30 caliber benchrest bullets using Niemi carbide dies, 7s ogive bullets typically using 1" j4 jackets but have made some using .920" jackets as well. We don't make a lot of bullets, but supply a few local shooters who have made us look good. Our bullets have won many matches, big and small, including the big upset this year at the 200-300 yard GROUP nationals HV grand that Dean Breeden won.

We do not own a Juenke machine, but do spin our bullets on a mechanical spinner to evaluate them from lot to lot. I just don't know what the value of the Juenke machine is, I've not heard a compelling argument for one yet. Have you found yours valuable?
Jim, I do not own one of these devices either; however, many people DO "spin" my bullets on the Juenke machine: invariably, the bullets are pronounced "superb" - undoubtedly due to the most excellent concentricity of Niemi dies. I can say that the Juenke device cannot/does not measure jacket wall run-out, which is generally referred to as TIR (total indicated run-out, which, via a dial indicator & mandrel CAN be accurately measured).

I know this by virtue of having "tricked" several Juenke owners into running bullets of various KNOWN (dial indicator measured) TIR; the devices/individuals were completely unable to accurately identify the varying degrees of TIR, which ranged from 0.0001" up to 0.0008"! Several segregated samples of each weight, along with a mixed sample were provided. Based upon these "tests", I concluded that this device mesures geometry - exterior geometry. I may assume a little credit for crossing the T's and dotting the I's, but the REAL reason the bullets Juenke so uniformly, rests in the extreme concentricity between the shank and nose sections of the Niemi carbide point-up dies.

My biggest issue with the Juenke machine: there is NO known calibration standard, nor a defined unit of measure; ie., is unit equal to 1/1,000 of an inch, 1/1,0000, etc. I have used precise measuring tools for all of my working career - evey single device was ALWAYS CALIBRATED to a KNOWN STANDARD. I am not saying that this device does not measure something - just that nobody has been able to tell me [exactly] what it does measure. Again, I believe that it probably measures variations in the origin (tangent) points of the nose and BT sections relative to the shank . . . and to some extent, the external concentricity of the bullet . . . I think.

Regressing slightly, I cannot disagree that bullets are "made" with the seating of the cores, however, I would add that the cores should be washed, then washed, then, washed again! R.G.

Last edited by R.G. Robinett; 11-09-2006 at 02:11 AM.
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