Originally Posted by Winchester 69
Neck turning is performed to fit the case neck to a custom chamber. You can check for variance in case neck thickness if you wish using a ball mic.
This is the best thing you can do for this brass.
For thickness variance, depending on cartridge & lot, I have seen Lapua worse than other brands.
The best I've seen, believe it or not, is Winchester's reloading 25WSSM brass.
The worst I've seen, was Lazeroni scramjet, Tubb 6XC, one very ugly Norma 223 case, and a single lot of Lapua 6br brass. But other lot's I use are very good.
I don't assume anything with brass.