M
Macaver
Guest
Whereas Waldo.....
For a long time after getting my K & M neck turner I drove myself nuts with concentricity issues that came up in my measurements during during the neck turning processes. In the end, I concluded that making such measurements during the turning operations was a waste of time, and that concentricity measurements were of value only after making the first one, or two, fireforming shots. (For that matter, like some others on this forum, I think neck turning after firing the cartridge at least once leads to better turning results, and that cases are "experienced" only after 2 firings.)
Here's what I found was throwing my concentricity completely off:.....Trying to take too deep a cut with the turner, or hitting a thicker section of brass while turning.
Our thin cartridge brass has some "plastic" characteristics and very little force is needed to "move it around". The extra force needed to continue the cut was twisting the case out of shape at the neck-shoulder junction. (This result may not apply to lathe-turned cases).
The solution, in my case, was to ease up on the cut and make a second finishing pass. But I also found out that some cases which got twisted by as much as .004" out of concentricity during a "too deep" turning pass came out just fine....0005" or less, after firing. (After the second firing, anything over .0005" at the neck goes into my scrap box.)
Frank Beckmann
For a long time after getting my K & M neck turner I drove myself nuts with concentricity issues that came up in my measurements during during the neck turning processes. In the end, I concluded that making such measurements during the turning operations was a waste of time, and that concentricity measurements were of value only after making the first one, or two, fireforming shots. (For that matter, like some others on this forum, I think neck turning after firing the cartridge at least once leads to better turning results, and that cases are "experienced" only after 2 firings.)
Here's what I found was throwing my concentricity completely off:.....Trying to take too deep a cut with the turner, or hitting a thicker section of brass while turning.
Our thin cartridge brass has some "plastic" characteristics and very little force is needed to "move it around". The extra force needed to continue the cut was twisting the case out of shape at the neck-shoulder junction. (This result may not apply to lathe-turned cases).
The solution, in my case, was to ease up on the cut and make a second finishing pass. But I also found out that some cases which got twisted by as much as .004" out of concentricity during a "too deep" turning pass came out just fine....0005" or less, after firing. (After the second firing, anything over .0005" at the neck goes into my scrap box.)
Frank Beckmann