I have great accuracy from the 140 grain Ballistic Tip at around 3080. I am shooting whitetail out to 600 yards. Is this a suitable bullet or should I go heavier? Also, people have told me (Sierra themselves) that the Matchkings and A-Max bullets don't have predictable expansion on big game. I am considering one of these bullets but don't want to make a pin hole through a deer. Any input would be appreciated.