Seems no consideration is ever given to the platform, but just the slight difference performance. Maybe someone's making 7# 7mags somewhere, but I've never seen one. Montana 7WSM will go 7# done. If an 8# rig is whats on the table, might as well fill the chamber to the top I say, and keep it simple.

I don't see an 8# 280 as worth the effort. If I were after 7#, then yes to the 280.

Remmie's box and throat in 7RM is perfect as far as I'm concerned.