BoydAllen
Gold $$ Contributor
Even with necks that are very close in thickness, cases vary in the amount of spring back that they have. I have not known anyone to anneal in short range, and so for that as well as your long range application, I think that your method makes good sense as a way to sort brass, particularly if one is trying to reduce differences in bullet pull. I guess that I will have to come up with some sort of tapered pin in 6mm if I am to test your method.
Years ago, a very experienced long range shooter told me that he has expander mandrels ground in half thousandth steps that he uses as the last step in his sizing process. He said that he was of the opinion that he got more uniform neck tension expanding up (slightly) after sizing down in the usual fashion.
As far as my personal experience goes, I have found that one can use an expander ball if the ID of the bushing or die combines with the neck thickness so that the expander is opening up the necks only .001. With this little work done by the expander the friction is not enough to cause the case to be made crooked in the process. I have used this to design chamber/ die systems such that with neck of a given thickness, there was .003 neck tension without the expander, and .002 with, both producing equally straight cases. I did this with one piece dies, and the results were very good.
My point in mentioning this is that I agree that a very small amount of expanding up may be beneficial, and help to negate issues caused by variations in neck thickness. IMO expanders have gotten a bad rap that should have been placed on overly small die IDs. None of this is conjecture, I have tested and measured it all.
Years ago, a very experienced long range shooter told me that he has expander mandrels ground in half thousandth steps that he uses as the last step in his sizing process. He said that he was of the opinion that he got more uniform neck tension expanding up (slightly) after sizing down in the usual fashion.
As far as my personal experience goes, I have found that one can use an expander ball if the ID of the bushing or die combines with the neck thickness so that the expander is opening up the necks only .001. With this little work done by the expander the friction is not enough to cause the case to be made crooked in the process. I have used this to design chamber/ die systems such that with neck of a given thickness, there was .003 neck tension without the expander, and .002 with, both producing equally straight cases. I did this with one piece dies, and the results were very good.
My point in mentioning this is that I agree that a very small amount of expanding up may be beneficial, and help to negate issues caused by variations in neck thickness. IMO expanders have gotten a bad rap that should have been placed on overly small die IDs. None of this is conjecture, I have tested and measured it all.