I have been shooting a 6.5 since 1964. Since the Barnes X bullets came out in the 1980's I have been using the 120gr exclusively for elk. I have a friend who he & his son use the 130gr TSX in their 270's. Each season we use these bullets which give complete penetration on elk even thru heavy bone. For deer the 6.5 100gr TTSX & the 110gr in the 270 give total penetration on the largest muley bucks. Either of these cals gives flat trajectories & absolute dependability. I see the Barnes TSX or Hornady GMX bullets enabling the 6.5 & 270 to perform like they were considerably larger.. For mice to moose I see these bullets in 6.5 & 270 to give dependable penetration with out the hard recoil of larger cals. I'm not trying to say anything negative against larger cals'. It's just that the progress in bullet technology changes the ability of a particular cal/bullet to perform.