Sorry, didn't read far enough down in the thread. The thing that I keep looking at is how precise, even and uniform the case failure is - as tho the brass had been cut. Most case failures don't happen along that "clean" a line. I also am with the others here - the point at which the case failed seems to indicate a lot of the case is unsupported by the chamber. I'm curious if you could measure the following all the front features of the bolt - the distance from the bolt face to the rim/bolt nose, the depth of the nose recess in the barrel, etc, etc. It just "seems" as tho the failure line on the case is too far forward of the case head. And in a Rem 700 action, I'm unsure of how the case head portion of that cartridge could have the brass flatten outward like that, unless the bolt has been modified to have a non-Remington extractor on it.