Re: New Brass, .243 Cracked neck
It sure is hard to tell from the pictures. I only get burn thru's when the brass has been reloaded many times. In fact it is the indicator I see mostly of worn out brass that needs replacement.
You know, it most certainly must be bad brass. Nothing else makes any sense. I'd call Winchester and see what they say. I'd not send them those pictures but an actual sample of the bad cases. If it was bad brass they may replace it. if it was a reloading error they may be able to point it out.