Do I need to anneal?
I'm puzzled, and need some input from a more experienced reloader than myself.
Case .338 Lapua necked down and fireformed to 7mm AM by Kirby's Dad.
This is the first full pressure load fired in this particular case. After firing, the case is cracked parallel to the case length on the shoulder, and the neck/shoulder junction shows smaller cracks around the case, again parallel to the case.
This case is part of a batch that was loaded by Kirby. Other rounds fired from the same loading batch did not exhibit this problem. The only difference is it is a year later; the ambient temp is 5°F higher and the altitude is roughly 3500 feet lower.
This is the first case that has exhibited this problem, from roughly 50 fired. I have two different lot numbers of cases, for a total of 200 cases. The remainder of the 200 cases have not been loaded for their first full pressure firing yet.
Is this something that I shouldn't worry about and consider it normal, or should I take steps to do something different?
Here's the load data:
Lapua brass, first full pressure firing.