I do little .303 loading but what I've done has given me good case life. I paid attention to headspacing and used the shoulder, as-is normal for me. I did not rely on the rim for headspacing. This loading I am referring to was for Military rifles #3's mostly having military barrels with sloppy, military chambers.

In each rifle, the shoulder had to be moved foreward considerably in order to hold the case firmly to push the ctg. back against the bolt when closing. The actual rim's headspace was sloppy just like all of the chamber's dimensions. Firing factory ammo in these rifles was a good way to limit case life top 2 or 3 shots, which some people think is normal. I chose not to think this way.

A custom barrel job on any action, such as this .35.303 job, should not have a sloppy chamber and should be headspaced for the brass available today - it is a custom job (I think) and should have been chambered to minimum specs for the brass that is going to be used - afterall, the customer paid for a custom job, not a "work in mud and blood" military rifle.

Hopefully, that is exactly what this rifle will show.