In my 6x284. Norma brass weights 5grs more then Lupua. Lupua has slightly greater case capacity . So if I should identical loads in each brand case with the Lapua have less pressure beings it has larger case capacity ?
In theory, yes, but there's some other factors involved here. Mike's right; check the water capacity and work the loads up. You're changing a component, and athat ALWAYS means you work it back up.