Long-term springback on sized necks?

Discussion in 'Reloading' started by tlk, Apr 20, 2011.

  1. tlk

    tlk Well-Known Member

    Apr 11, 2008
    Something odd: I pulled out some cases that I had annealed, neck sized three months ago to reload. These cases were confirmed at .306 ID neck with a pin guage at the time.

    Last night I pull them out to reload and do a double check on the dims - the pin gauge slips around in there pretty good instead of a slight drag and an "air piston" pushback effect when I cover the primer hole and press down on the pin gauge in the shell. This is a measurement that I am fairly OCD about so it stood out. Wasn't .307 or anything, but it was a noticeable change.

    Is this normal over time? Would there be any real effects on neck tnesion with a loaded round?

  2. ken snyder

    ken snyder Well-Known Member

    Jul 26, 2010
    I've noticed that pin gauging soft materials is not very repeatable, After the first time it is performed on brass. The gauge itself can enlarge diameters ( from slight interference to a slip fit), particularly when done by hand. Temperature: cold brass, warm pin and then the other way around can account for perhaps as much as .0005 in feel. other than slight oxidization as a friction modifier you still have really close to the same hole that you measured originally. The big culprit is doing it twice with a long interval between measurements and doing it by feel!
  3. loaders_loft

    loaders_loft Well-Known Member

    Feb 11, 2008
    Probably just a temp change, if you are like me, loading in the garage. It was cold in january...