Thread: Excessive head spacing 7mm RM - can it still be used

Originally Posted by gundoc

7mm Rem Mag headspaces on the belt, not the shoulder so they will be OK to use and will fire-form to the chamber.

This.

Although common practise now is to let the brass grow over consecutive firings until it headspaces off the shoulder, not the belt.

However, you will probably need the Larry Wills/Innovative Technologies Belted Magnum Collet die to get the area just ahead of the belt sized down (after those subsequent firings) to achieve this.

Peterson now offers 'Long' magnum brass with the explicit intention of not headspacing off the belt, but the shoulder.

https://youtu.be/XTL-Sk5dNf8