Headspacing X Caliber 7mm Rem Mag

I know belted magnums headspace off the belt on the first firing, and then the shoulder can be used for reloading. I have also read that SAAMI is usually larger than actual brass/belt distance, so extra headspace is inherent.

Is it advisable or contraindicated to headspace with a go gauge that will allow extra room for shoulder to blow out, or use a regular go gauge to set install new barrel?

I have been unable to find a 7mm rem mag go gauge btw.

Head space on the belt, resize to the the chamber.

https://www.midwayusa.com/product/10...space-go-gauge

In stock ships tomorrow.

Thanks... I saw a different brand one out of stock. Didnt realize that one was available

If you don't feel like buying the gauges, you can rent them.

https://4drentals.com/product/7mm-remington-magnum/

You'll need both the go and the no go gauge to headspace a barrel.