Sticky Bolt

[fguffey]

There are some good annealing articles on the main site. You definitely don't want to soften the base. Just the top 1/3 or so. Your new Lapua brass has the color you want to duplicate.

There was a time working the brass in the case head was not a good ideal.

F. Guffey

 

[Big Mc]

I would use a body die. To resize the whole case..

 

[mikecr]

The reason why NS only doesn't work for folks is poor or no planning up front.
No doubt in my mind your chamber clearance near web is far too large for neck sizing only.
With this, multiple firings led to yielding of near web brass(absolutely predictable). If it yielded >~2thou, which you said it did, it's forever changed. Yeah you can squish it back down with a lot of FL sizing, but you'll have to do that from then on(because the brass is still changed).
Then, with a lot of FL sizing for management of this, you'll end up trimming a lot, and you've changed cases again(by the amount trimmed) -EVERY TIME.

When you chose your chamber, you chose your path (same as everyone else).
It's a 338LM. Big case area, high body taper, low shoulder angle, SAAMI clearances. Nobody can get away with NS only for this.
Your best plan would have included a chamber reamer with rational clearances, and sending twice fired brass to a custom die maker.

It isn't that brass can't last forever as suggested earlier. It's that it takes understanding, a plan, and control over what we're doing.
After all, our brass cases are what we make of them. It's not an abstract.