Well, I finally got a chance to try out the new rifle yesterday (more about that later!) with a range of homeloads. 243, N140, 87gr bullet.
From the lightest loads right through to the near maximum I was finding burn marks not only on the neck but also on the shoulder of the case.
I know this can be a sign of low pressure, but the primers were fine in all cases, no cratering, no backed out primers etc.
There were no burn marks at all on the sides of the cases.
Oddly, with the starting load the burn marks stop neatly 2/3rds of the way down the shoulder. With the heavier loads it was all the way down the shoulder.
The cases are new winchester never fired. I full length resized, trimmed etc before loading.
I did not crimp the bullets.
I was also zeroing at the same time, the groups were around 2 inches at 100 yds - shots taken from a not very comfortable position I might add, in the rain.
What are your thoughts on this shoulder burn issue?