I have been using the Sierra 120 gr in my 264 mag & other 6.5's since back in the 1960's. Have taken several truck loads of muley's with them without any problems. What little I tried the Nosler BT I found them to be a bit fragile & tend to blow up destroying good meat. Rib cage shots with the Nosler some times cause the bullet to fragment to the point that shards of bullet punctured the gut. Never had that happen with a Sierra even at 264 mag velocity. For real toughness the 100gr mono's like the Barnes do a fantastic job on even heavy bodied muley's.
