So I took a chamber cast of my AR barrel today. I bought the barrel new as a Wilson match grade barrel. Haven't shot it much yet. Its 20" stainless hbar style, 1:7 twist. Anyway, the one thing that stands out to me on the chamber cast is that the case neck portion is about .030" longer then SAAMI cartridge spec. How bad is that for accuracy?
If I could find good brass with necks that long I'd say it is an advantage but I've never seen such brass. It would take a lot of firings to get brass to grow that much to fill the chamber neck.
Any thoughts on the matter?