Doesn’t that cartride headspace on the belt? Is it a resizing issue at or near the case head? Just wondering why the neck would be such an issue, but then I really know very little about this cartridge.
It is a double belted magnum case. The issue is not the design of the case except for the tolerances. Very tight.
The case neck shape is unique (as far as I know) the chamber and case tolerance is pure precision.
Case illustrations showing neck and double belted base:
Not all reloading dies will work. More than a few people have had trouble with the issue. I read a comment by a factory tech at RCBS stating they got quite a few calls about it. Solution was turning the die 1/2 turn more than normal and applying the maximum pressure on the press until it rolled over. (the solution worked with the gun that my gunsmith friend was working on)
There were statements of others that had the issue saying Lee dies might not be able to reload it where some rifles would close the bolt.
Now, this particular rifle was a non-factory version, custom built by a gunsmith. It was a beautiful job of workmanship. Wildcat stuff is never simple.
