Originally Posted by elkhunter11

The rate of expansion often changes as the bullet penetrates,but the actual expansion begins the instant the bullet strikes a media with enough resistance to initiate expansion.The thick jacket in the nose of a Berger bullet does not totally delay expansion,rather it controls the rate of expansion.The result is that the bullet initially expands quite slowly,then the rate of expansion increases dramatically as the nose opens up.The bullet may not expand rapidly upon first contact,but it is still expanding.