Re: Carbon on the outside of the case neck after firing?
I always get carboned necks. I shoot lapau brass, neck sized, fire formed, and nothing changes it. I have loads that produced sticky bolt lift, flat primers, and extractor marked, still carboned up. So the pressure was definitely there.
I hate it, but the rifle shoots well so I don't bother to change anything. I thought it might be dirty burning powder but 4350 is not typically described as dirty and you have the issue, so who knows.