RE: 325 WSM Vs 300 WSM Vs 7mm Rem Mag Vs 300 Win Mag Vs 280 Rem
It has taken me over 20 years to feel confident that I can make the shot at the distances you have listed. That is a long way in a hunting situation. There is a lot of difference between fair weather bench shooting and real weather hunting. For shooting the distances you arespeaking of it takes a lot of preparation. But it is by no means impossible. You definitely need to buy quality products to be able to do this consistently(and humanely).
My cartridge choice(not caliber) is the 300 WSM for my long distance deer rifle. I would also consider the 300 Win Mag as adequate. I do not consider any "caliber" below 30 caliber to be acceptable. But the 7 mm caliber is used by many. Tom.