Looks like you have two shoulders....
I shot a 7mm mag for years stoked full tilt....neck sized only without any issues. The primer pockets will be the first thing to go.
After about 3 loadings I just pitched the brass.
The belted magnums head space on the belt....why the need to bump the shoulder ?
You sort of missed the boat, here. Headspacing on the belt can cause excessive case stretch through the body, leading to case-head separation, etc.
Only if it has excessive headspace in the first place (on the belt). Using the shoulder instead for headspacing can help fix this problem.
Not an option for something using a case without a shoulder, like 458WM for example, but the cases in a 458WM with proper headspace will last for yonks, until the neck cracks (typically).
