Long-term springback on sized necks?

[tlk]

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?

Thanks

 

[ken snyder]

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!

 

[loaders_loft]

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