Hondo and CT,
Are 100% spot on. The only thing barrel heat does is show you of there is stress in the system that needs to be fixed. Groups grow when you fire more than 3 rounds because 3 rounds aren't a "group". People use 3 rounds because they can lie to themselves. The rifles don't know whether it's the first round or the 15th. 10 rounds offer a good idea of where any one round will bland. There is no such thing as a "cold bore" shot. A sub 2 MOA 308Win Montana is about as good or better than what most will do.
Cut the bs, shoot ten and know what the rifle will do.
