Great discussion here. I've got a huge hard on for the 7mm bullet selection and will build my next bolt gun in 7mm for sure.
I picked 7mm/300WSM for one simple reason: brass selection. If Lapua made straight 7mm WSM
brass it wouldn't be such an issue, but the 7mm/300 WSM
unlocks high end brass, just need to fire form and turn the necks.
Plus, the 7mm/300 WSM REAMER has dimentions for a longer neck. get the basic drawing of your smith's reamer and then trim brass to a few thou of that length.