OK, This is a photo of two edge cases for comparison. The one on the left is unfired and the one on the right is the case that I managed to get to fire in my new rifle. Both cases were made from Remington 300 RUM brass.
As you can see the fired case has had the shoulder pushed a considerable way forward. There must be a lot of slop in the chamber. about 0.080" as I measure it. I won't be attempting to fire this rifle again until the gun smith has fixed it in two days time.
I think when he installed the oversize recoil lug, he forgot to take the extra thickness into account? Maybe? Who knows?
Unfortunately he lives 7 hours drive away, so I have to drive up to his place, wait for him to fix it then drive 7 hours home again.
Anyone want to test fire it for me??????? I now have a bad flinch.