Originally Posted by MontanaRifleman
Took some pics but having trouble downloading. Will try to get it worked out tomorrow, maybe use my phone camera.
The bullets are seated down below the shoulder/neck junction so that would prevent visible shrinkage. Used my percussion bullet puller to pull one of them and it didn't require anymore effort than recently seated bullets with neck tensions about .002 give or take. Also, no sign of oxidation on bullet or inside the case neck.
This also happened with 160 Nosler Partitions loaded about the same time. However, all (50) of them had a wrinkled (bulged) neck and almost none have wrinkled shoulders. The Balistic Tips were loaded into Fed Brass and the NP's into Rem.
At that time, my habit was to clean the inside of the necks with a bronze brush which I do now with a nylon brush.
Ok from teh sound of it you have not experienced bad age hardening that's good. I said it was unpredictable .
As far as bulged necks go then the problem may be incorrect adjustment of the bullet seating die . If you have the die body down too far when you push the bullet into the case the end of the neck can hit up against the end of the die .
A little bit might just crimp the bullet but a lot will push the neck back and damage it.
If you back the seater stem out and die off then run an empty case of correct lenght into the die . Run the body of the die down until it stops on the case then back off one 1/2 turn that will give you about .0357 clearance . Lock the die body then go about adjusting the seater stem to give correct seating depth.